@article{dieffenderfer_brewer_noonan_smith_eichenlaub_haley_jacks_lobaton_neupert_hess_et al._2023, title={A Wearable System for Continuous Monitoring and Assessment of Speech, Gait, and Cognitive Decline for Early Diagnosis of ADRD}, ISSN={["1558-4615"]}, DOI={10.1109/EMBC40787.2023.10339986}, abstractNote={Early detection of cognitive decline is essential to study mild cognitive impairment and Alzheimer’s Disease in order to develop targeted interventions and prevent or stop the progression of dementia. This requires continuous and longitudinal assessment and tracking of the related physiological and behavioral changes during daily life. In this paper, we present a low cost and low power wearable system custom designed to track the trends in speech, gait, and cognitive stress while also considering the important human factor needs such as privacy and compliance. In the form factors of a wristband and waist-patch, this multimodal, multi-sensor system measures inertial signals, sound, heart rate, electrodermal activity and pulse transit time. A total power consumption of 2.6 mW without any duty cycling allows for more than 3 weeks of run time between charges when 1500 mAh batteries are used.Clinical Relevance— Much earlier detection of Alzheimer’s disease and related dementias may be possible by continuous monitoring of physiological and behavioral state using application specific wearable sensors during the activities of daily life.}, journal={2023 45TH ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE & BIOLOGY SOCIETY, EMBC}, author={Dieffenderfer, James and Brewer, Alec and Noonan, Maxwell A. and Smith, Madeline and Eichenlaub, Emily and Haley, Katarina L. and Jacks, Adam and Lobaton, Edgar and Neupert, Shevaun D. and Hess, Thomas M. and et al.}, year={2023} }
 @article{zhao_stephany_han_ahmmed_bozkurt_jia_2023, title={A Wireless Multimodal Physiological Monitoring ASIC for Injectable Implants}, ISSN={["1930-8833"]}, DOI={10.1109/ESSCIRC59616.2023.10268719}, abstractNote={This paper presents a wireless multimodal physiological monitoring ASIC fabricated in a CMOS 180 nm process. The application-specific integrated circuit (ASIC) is sized to be within the form factor of an injectable microchip implant and can measure electrocardiography (ECG), photoplethysmography (PPG), and body temperature. The low-power circuit design enables the ASIC to wirelessly receive the required power, 155.3 μW on average, via an inductive link. The ECG analog frontend (AFE) has input-referred noise (IRN) of 3.1 μVrms within 0. 3-1kHz. To measure PPG, the LED driver employs a switched-capacitor-based architecture as an energy-efficient and safe method to deliver current pulses in milliampere order to an LED. An integrator-based AFE amplifies the photodetector (PD) current with 47 pArms IRN within 0.1-10 Hz. Recorded physiological signals are digitized by a 10-bit successive approximation register (SAR) analog-to-digital converter (ADC) with an 8.79-bit effective number of bits (ENOB), followed by a backscatter-based data telemetry, which transmits data via intermediate-frequency (IF)-assisted load shift keying (LSK) modulation. The overall ASIC performance has been evaluated in vivo on anesthetized rats.}, journal={IEEE 49TH EUROPEAN SOLID STATE CIRCUITS CONFERENCE, ESSCIRC 2023}, author={Zhao, Linran and Stephany, Raymond G. and Han, Yiming and Ahmmed, Parvez and Bozkurt, Alper and Jia, Yaoyao}, year={2023}, pages={305–308} }
 @article{barahona_mills_hernandez_bozkurt_carpenter_lobaton_2023, title={Adolescent Asthma Monitoring: A Preliminary Study of Audio and Spirometry Modalities}, ISSN={["1558-4615"]}, DOI={10.1109/EMBC40787.2023.10340643}, abstractNote={Asthma patients’ sleep quality is correlated with how well their asthma symptoms are controlled. In this paper, deep learning techniques are explored to improve forecasting of forced expiratory volume in one second (FEV1) by using audio data from participants and test whether auditory sleep disturbances are correlated with poorer asthma outcomes. These are applied to a representative data set of FEV1 collected from a commercially available sprirometer and audio spectrograms collected overnight using a smartphone. A model for detecting nonverbal vocalizations including coughs, sneezes, sighs, snoring, throat clearing, sniffs, and breathing sounds was trained and used to capture nightly sleep disturbances. Our preliminary analysis found significant improvement in FEV1 forecasting when using overnight nonverbal vocalization detections as an additional feature for regression using XGBoost over using only spirometry data.Clinical relevance— This preliminary study establishes up to 30% improvement of FEV1 forecasting using features generated by deep learning techniques over only spirometry-based features.}, journal={2023 45TH ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE & BIOLOGY SOCIETY, EMBC}, author={Barahona, Jeffrey A. and Mills, Katie and Hernandez, Michelle and Bozkurt, Alper and Carpenter, Delesha and Lobaton, Edgar J.}, year={2023} }
 @article{wu_nichols_foster_martin_dieffenderfer_enomoto_lascelles_russenberger_brenninkmeyer_bozkurt_et al._2023, title={An Exploration of Machine Learning Methods for Gait Analysis of Potential Guide Dogs}, url={https://doi.org/10.1145/3637882.3637883}, DOI={10.1145/3637882.3637883}, abstractNote={Gait analysis is important for guide dog organizations, as ideal guide dogs have a smooth and efficient gait, where they can also easily shift between and maintain various gaits. Gait quality and natural traveling speed are two of the multiple factors important in matching a guide dog to its visually impaired handler. Gait evaluation typically includes subjective visual observation of the dog or objective assessments obtained from special-designed equipment. Guide dog organizations need a method to easily collect and analyze objective data of gait information. In this work, we explored how various machine learning models could learn and analyze gait patterns from inertial measurements data that were collected during two different data collection experiments using a wearable sensor device. We also evaluated how well each machine learning model could generalize behavior patterns from various dogs under different environments. Additionally, we compared how sensor placement locations could affect gait prediction performance by attaching the sensor device to the dog’s neck and back area respectively. The tested machine learning models were able to classify different gaits in the range of 42% to 91% in terms of accuracy, and predict various gait parameters with an error rate ranging from 14% to 29% depending on the setup. Furthermore, we also observed that using behavior data collected from the neck region contains more movement information than the back area. By performing a cross-dataset generalization test on the machine learning models, we found that even with performance drop, the models were able to learn gait-specific behavior patterns that are generalizable for different dogs. Although the results were preliminary, the proposed gait analysis exploration still showed promising potential for studying behavior patterns of candidate guide dogs.}, journal={TENTH INTERNATIONAL CONFERENCE ON ANIMAL-COMPUTER INTERACTION, ACI 2023}, author={Wu, Yifan and Nichols, Colt and Foster, Marc and Martin, Devon and Dieffenderfer, James and Enomoto, Masataka and Lascelles, B. Duncan X. and Russenberger, Jane and Brenninkmeyer, Gerald and Bozkurt, Alper and et al.}, year={2023} }
 @article{queener_ahmmed_victorio_twiddy_dehn_brewer_lobaton_bozkurt_pozdin_daniele_2023, place={Vienna, Austria}, title={Conformal Micropatterned Organic-Metal Electrodes for Physiological Recording}, ISSN={["1930-0395"]}, url={http://dx.doi.org/10.1109/sensors56945.2023.10324963}, DOI={10.1109/SENSORS56945.2023.10324963}, abstractNote={Conformal electrodes provide a soft and conforming interface with the skin for reduced impedance, comfortable skin contact, and improved signal quality compared to commercial electrodes. In this paper, we present conformal micropatterned organic-metal (CMOM) electrodes and our investigation on the effect of perforation micropatterning and PEDOT:PSS coating. CMOM electrodes were characterized then evaluated in vivo against commercial-off-the-shelf electrodes. PEDOT:PSS was found to reduce the overall impedance in each electrode variant, resulting in a >97% decrease in impedance at low frequencies. The change in impedance at high frequencies was not significant for the control or $30\ \mu \mathrm{m}$ vias electrodes, but the impedance was significantly greater following EPD for $60\ \mu \mathrm{m}$ vias electrodes.}, journal={2023 IEEE SENSORS}, author={Queener, Kirstie M. and Ahmmed, Parvez and Victorio, Mauro and Twiddy, Jack and Dehn, Ashley and Brewer, Alec and Lobaton, Edgar and Bozkurt, Alper and Pozdin, Vladimir and Daniele, Michael}, year={2023} }
 @article{ahmmed_reynolds_bozkurt_regmi_2023, title={Continuous heart rate variability monitoring of freely moving chicken through a wearable electrocardiography recording system}, volume={102}, ISSN={["1525-3171"]}, url={https://doi.org/10.1016/j.psj.2022.102375}, DOI={10.1016/j.psj.2022.102375}, abstractNote={Identification and quantification of stress and stress inducing factors are important components of animal welfare assessment and essential parts of poultry management. Measurement of the autonomic nervous system's influence on cardiac function using heart rate and heart rate variability (HR/HRV) indices can provide a non-invasive assessment of the welfare status of an animal. This paper presents a preliminary study showing the feasibility of continuous long-term measurement of HR/HRV indices in freely moving chicken. We developed and evaluated an electrocardiography (ECG) based HR/HRV recording system that can be used as a poultry wearable backpack for research studies. The backpack system was first validated against a commercial ECG amplifier, and the corresponding estimations of HR values matched well with each other. Then, an in vivo proof-of-concept experiment was conducted on floor-reared chickens to collect ECG data for 2 weeks. The extracted HR/HRV values show strong alignment with circadian patterns and well-defined sleep cycles. Wearable devices, like the backpack ECG system used in this study, may be best suited for application in freely moving poultry to get an insight into circadian abnormalities and sleep quality for stress and welfare management.}, number={2}, journal={POULTRY SCIENCE}, author={Ahmmed, P. and Reynolds, J. and Bozkurt, A. and Regmi, P.}, year={2023}, month={Feb} }
 @article{chen_attri_barahona_hernandez_carpenter_bozkurt_lobaton_2023, title={Robust Cough Detection With Out-of-Distribution Detection}, volume={27}, ISSN={["2168-2208"]}, url={https://doi.org/10.1109/JBHI.2023.3264783}, DOI={10.1109/JBHI.2023.3264783}, abstractNote={Cough is an important defense mechanism of the respiratory system and is also a symptom of lung diseases, such as asthma. Acoustic cough detection collected by portable recording devices is a convenient way totrack potential condition worsening for patients who have asthma. However, the data used in building current cough detection models are often clean, containing a limited set of sound categories, and thus perform poorly when they are exposed to a variety of real-world sounds which could be picked up by portable recording devices. The sounds that are not learned by the model are referred to as Out-of-Distribution (OOD) data. In this work, we propose two robust cough detection methods combined with an OOD detection module, that removes OOD data without sacrificing the cough detection performance of the original system. These methods include adding a learning confidence parameter and maximizing entropy loss. Our experiments show that 1) the OOD system can produce dependable In-Distribution (ID) and OOD results at a sampling rate above 750 Hz; 2) the OOD sample detection tends to perform better for larger audio window sizes; 3) the model's overall accuracy and precision get better as the proportion of OOD samples increase in the acoustic signals; 4) a higher percentage of OOD data is needed to realize performance gains at lower sampling rates. The incorporation of OOD detection techniques improves cough detection performance by a significant margin and provides a valuable solution to real-world acoustic cough detection problems.}, number={7}, journal={IEEE JOURNAL OF BIOMEDICAL AND HEALTH INFORMATICS}, author={Chen, Yuhan and Attri, Pankaj and Barahona, Jeffrey and Hernandez, Michelle L. and Carpenter, Delesha and Bozkurt, Alper and Lobaton, Edgar}, year={2023}, month={Jul}, pages={3210–3221} }
 @article{martin_roberts_bozkurt_2023, title={Toward In-the-Field Canine Manifold Learning: Data Fusion for Evaluation of Potential Guide Dogs}, DOI={10.1145/3637882.3637898}, journal={TENTH INTERNATIONAL CONFERENCE ON ANIMAL-COMPUTER INTERACTION, ACI 2023}, author={Martin, Devon and Roberts, David and Bozkurt, Alper}, year={2023} }
 @article{holder_nichols_summers_roberts_bozkurt_2023, title={Towards a Multimodal Synchronized System for Quantifying Psychophysiological States in Canine Assisted Interactions}, DOI={10.1145/3637882.3637886}, journal={TENTH INTERNATIONAL CONFERENCE ON ANIMAL-COMPUTER INTERACTION, ACI 2023}, author={Holder, Timothy and Nichols, Colt and Summers, Emily and Roberts, David L. and Bozkurt, Alper}, year={2023} }
 @article{reynolds_williams_martin_readling_ahmmed_huseth_bozkurt_2022, title={A Multimodal Sensing Platform for Interdisciplinary Research in Agrarian Environments}, volume={22}, ISSN={["1424-8220"]}, url={https://doi.org/10.3390/s22155582}, DOI={10.3390/s22155582}, abstractNote={Agricultural and environmental monitoring programs often require labor-intensive inputs and substantial costs to manually gather data from remote field locations. Recent advances in the Internet of Things enable the construction of wireless sensor systems to automate these remote monitoring efforts. This paper presents the design of a modular system to serve as a research platform for outdoor sensor development and deployment. The advantages of this system include low power consumption (enabling solar charging), the use of commercially available electronic parts for lower-cost and scaled up deployments, and the flexibility to include internal electronics and external sensors, allowing novel applications. In addition to tracking environmental parameters, the modularity of this system brings the capability to measure other non-traditional elements. This capability is demonstrated with two different agri- and aquacultural field applications: tracking moth phenology and monitoring bivalve gaping. Collection of these signals in conjunction with environmental parameters could provide a holistic and context-aware data analysis. Preliminary experiments generated promising results, demonstrating the reliability of the system. Idle power consumption of 27.2 mW and 16.6 mW for the moth- and bivalve-tracking systems, respectively, coupled with 2.5 W solar cells allows for indefinite deployment in remote locations.}, number={15}, journal={SENSORS}, author={Reynolds, James and Williams, Evan and Martin, Devon and Readling, Caleb and Ahmmed, Parvez and Huseth, Anders and Bozkurt, Alper}, year={2022}, month={Aug} }
 @article{martin_holder_nichols_park_roberts_bozkurt_2022, title={Comparing Accelerometry and Depth Sensing-Based Computer Vision for Canine Tail Wagging Interpretation}, DOI={10.1145/3565995.3566025}, abstractNote={This paper presents a preliminary effort to evaluate alternative sensing modalities for automated, high-resolution tracking of dog tail position and movement as a behavioral communication tool. We compare two different methods: (1) inertial measurement devices placed on dog outfits, and (2) remotely positioned cameras supported with custom vision-based tail wag detection algorithms. The small size and non-invasiveness of the inertial sensors and the non-contact and remote nature of the camera system both promote subject comfort and continuous signal acquisition while not affecting the mechanics of dog tail movement. The preliminary findings support that the higher-resolution and continuous interpretations on the dog tail movements and positions can pave the way for assessing their emotional states and designing more appropriate training and play environments.}, journal={NINTH INTERNATIONAL CONFERENCE ON ANIMAL-COMPUTER INTERACTION, ACI 2022}, author={Martin, Devon and Holder, Timothy and Nichols, Colt and Park, Jeremy and Roberts, David and Bozkurt, Alper}, year={2022} }
 @article{holder_rahman_summers_roberts_wong_bozkurt_2022, title={Contact-Free Simultaneous Sensing of Human Heart Rate and Canine Breathing Rate for Animal Assisted Interactions}, DOI={10.1145/3565995.3566039}, abstractNote={Animal Assisted Interventions (AAIs) involve pleasant interactions between humans and animals and can potentially benefit both types of participants. Research in this field may help to uncover universal insights about cross-species bonding, dynamic affect detection, and the influence of environmental factors on dyadic interactions. However, experiments evaluating these outcomes are limited to methodologies that are qualitative, subjective, and cumbersome due to the ergonomic challenges related to attaching sensors to the body. Current approaches in AAIs also face challenges when translating beyond controlled clinical environments or research contexts. These also often neglect the measurements from the animal throughout the interaction. Here, we present our preliminary effort toward a contact-free approach to facilitate AAI assessment via the physiological sensing of humans and canines using consumer-grade cameras. This initial effort focuses on verifying the technological feasibility of remotely sensing the heart rate signal of the human subject and the breathing rate signal of the dog subject while they are interacting. Small amounts of motion such as patting and involuntary body shaking or movement can be tolerated with our custom designed vision-based algorithms. The experimental results show that the physiological measurements obtained by our algorithms were consistent with those provided by the standard reference devices. With further validation and expansion to other physiological parameters, the presented approach offers great promise for many scenarios from the AAI research space to veterinary, surgical, and clinical applications.}, journal={NINTH INTERNATIONAL CONFERENCE ON ANIMAL-COMPUTER INTERACTION, ACI 2022}, author={Holder, Timothy and Rahman, Mushfiqur and Summers, Emily and Roberts, David and Wong, Chau-Wai and Bozkurt, Alper}, year={2022} }
 @article{wang_foster_bozkurt_roberts_2022, title={Motion-Resilient ECG Signal Reconstruction from a Wearable IMU through Attention Mechanism and Contrastive Learning}, url={https://doi.org/10.1145/3565995.3566037}, DOI={10.1145/3565995.3566037}, abstractNote={Wearable electrocardiogram (ECG) sensors can detect dogs’ heartbeat signals and have proven useful in monitoring dogs’ welfare and predicting temperament scores in structured evaluations of potential guide dog puppies. Despite advances in the ergonomics, performance, and usability of ECG sensor technologies specifically designed for dogs, deploying those systems in the real world imposes challenges such as training human operators to ensure electrodes’ proper contact with the skin and, especially in the case of puppies, socialization to achieve comfort and reduce behavioral inhibition. Seismocardiogram signal is an alternate modality for heartbeat signals and is acquired using the Inertial Measurement Unit (IMU), which is commercially available, widely deployed, and does not require skin-contact. However, the extracted signals from IMU are subject to heavy influences from motion and other noise sources. In this paper, we present a method that enables extracting the similar physiological parameters ECG provides using easier-to-deploy IMU sensors. We propose and evaluate a machine learning framework that reconstructs ECG signals from IMU signals even under moderate to heavy movements. Our study investigated two artificial neural network architectures to overcome severe noise artifacts in the IMU signal resulting from dogs’ movements and environmental factors. The first architecture combines the attention mechanism and convolution layers to extract important features from the temporal IMU input. The second architecture adapts contrastive representation learning to the regression problem and learns a more effective embedding for the ECG reconstruction. The qualitative inspection and quantitative analysis based on F1 scores of the R-peak alignment demonstrate the effectiveness of the two proposed models in removing motion noises and reconstructing realistic ECG signals, achieving an F1 score of 0.72 in the best case compared to 0.29 from the baseline.}, journal={NINTH INTERNATIONAL CONFERENCE ON ANIMAL-COMPUTER INTERACTION, ACI 2022}, author={Wang, Jianxun and Foster, Marc and Bozkurt, Alper and Roberts, David L.}, year={2022} }
 @article{foster_wu_roberts_bozkurt_2022, title={Preliminary Evaluation of a System with On-Body and Aerial Sensors for Monitoring Working Dogs}, volume={22}, ISSN={["1424-8220"]}, url={https://doi.org/10.3390/s22197631}, DOI={10.3390/s22197631}, abstractNote={This paper presents a system for behavioral, environmental, and physiological monitoring of working dogs using on-body and aerial sensors. The proof of concept study presented here includes two trained dogs performing nine scent detection tasks in an uncontrolled environment encompassing approximately two acres. The dogs were outfitted with a custom designed wearable harness to monitor their heart rate, activity levels and skin temperature. We utilized a commercially available micro-air vehicle to perform aerial sensing by tracking the terrain and movement of the dog in the outdoor space. The dogs were free to explore the space working at maximal speeds to complete a scent-based search-and-retrieval task. Throughout the experiment, the harness data was transferred to a base station via Wi-Fi in real-time. In this work, we also focused on testing the performance of a custom 3D electrode with application specific ergonomic improvements and adaptive filter processing techniques to recover as much electrocardiography data as possible during high intensity motion activity. We were able to recover and use 84% of the collected data where we observed a trend of heart rate generally increasing immediately after successful target localization. For tracking the dogs in the aerial video footage, we applied a state-of-the-art deep learning algorithm designed for online object tracking. Both qualitative and quantitative tracking results are very promising. This study presents an initial effort towards deployment of on-body and aerial sensors to monitor the working dogs and their environments during scent detection and search and rescue tasks in order to ensure their welfare, enable novel dog-machine interfaces, and allow for higher success rate of remote and automated task performance.}, number={19}, journal={SENSORS}, author={Foster, Marc and Wu, Tianfu and Roberts, David L. and Bozkurt, Alper}, year={2022}, month={Oct} }
 @article{twiddy_taggart_reynolds_sharkey_rufty_lobaton_bozkurt_daniele_2022, title={Real-Time Monitoring of Plant Stalk Growth Using a Flexible Printed Circuit Board Sensor}, ISSN={["1930-0395"]}, DOI={10.1109/SENSORS52175.2022.9967167}, abstractNote={Monitoring of plant growth within agriculture is essential for ensuring the survival of crops and optimization of resources in the face of environmental and industrial challenges. Herein, we describe a low-cost and easily deployable flexible circuit board sensor for measurement of plant stalk growth, providing for remote tracking of plant development on an industrial scale. Three circuit topologies and measurement strategies - “ladder-type,” “multiplex-type,” and “mixed-type” - are initially assessed off-plant in a simulated growth experiment. Further development of the “multiplex-type” sensor and on-plant validation demonstrates its ability to quantify stalk growth as a proxy for plant development.}, journal={2022 IEEE SENSORS}, author={Twiddy, Jack and Taggart, Matthew and Reynolds, James and Sharkey, Chris and Rufty, Thomas and Lobaton, Edgar and Bozkurt, Alper and Daniele, Michael}, year={2022} }
 @article{wu_holder_foster_williams_enomoto_lascelles_bozkurt_roberts_2022, title={Spatial and Temporal Analytic Pipeline for Evaluation of Potential Guide Dogs Using Location and Behavior Data}, url={https://doi.org/10.1145/3565995.3566033}, DOI={10.1145/3565995.3566033}, abstractNote={Training guide dogs for visually-impaired people is a resource-consuming task for guide dog schools. This task is further complicated by a dearth of capabilities to objectively measure and analyze candidate guide dogs’ temperaments as they are placed with volunteer raisers away from guide dog schools for months during the raising process. In this work, we demonstrate a preliminary data analysis workflow that is able to provide detailed information about candidate guide dogs’ day to day physical exercise levels and gait activities using objective environmental and behavioral data collected from a wearable collar-based Internet of Things device. We trained and tested machine learning models to analyze different gait types including walking, pacing, trotting and mixture of walk and trot. By analyzing data both spatially and temporally, a location and behavior summary for candidate dogs is generated to provide insight for guide dog training experts, so that they can more accurately and comprehensively evaluate the future success of the candidate. The preliminary analysis revealed movement patterns for different location types which reflected the behaviors of candidate guide dogs.}, journal={NINTH INTERNATIONAL CONFERENCE ON ANIMAL-COMPUTER INTERACTION, ACI 2022}, author={Wu, Yifan and Holder, Timothy and Foster, Marc and Williams, Evan and Enomoto, Masataka and Lascelles, B. Duncan X. and Bozkurt, Alper and Roberts, David L.}, year={2022} }
 @article{saha_songkakul_knisely_yokus_daniele_dickey_bozkurt_velev_2022, title={Wireless Wearable Electrochemical Sensing Platform with Zero- Power Osmotic Sweat Extraction for Continuous Lactate Monitoring}, volume={7}, ISSN={["2379-3694"]}, url={https://doi.org/10.1021/acssensors.2c00830}, DOI={10.1021/acssensors.2c00830}, abstractNote={Wearable and wireless monitoring of biomarkers such as lactate in sweat can provide a deeper understanding of a subject's metabolic stressors, cardiovascular health, and physiological response to exercise. However, the state-of-the-art wearable and wireless electrochemical systems rely on active sweat released either via high-exertion exercise, electrical stimulation (such as iontophoresis requiring electrical power), or chemical stimulation (such as by delivering pilocarpine or carbachol inside skin), to extract sweat under low-perspiring conditions such as at rest. Here, we present a continuous sweat lactate monitoring platform combining a hydrogel for osmotic sweat extraction, with a paper microfluidic channel for facilitating sweat transport and management, a screen-printed electrochemical lactate sensor, and a custom-built wireless wearable potentiostat system. Osmosis enables zero-electrical power sweat extraction at rest, while continuous evaporation at the end of a paper channel allows long-term sensing from fresh sweat. The positioning of the lactate sensors provides near-instantaneous sensing at low sweat volume, and the custom-designed potentiostat supports continuous monitoring with ultra-low power consumption. For a proof of concept, the prototype system was evaluated for continuous measurement of sweat lactate across a range of physiological activities with changing lactate concentrations and sweat rates: for 2 h at the resting state, 1 h during medium-intensity exercise, and 30 min during high-intensity exercise. Overall, this wearable system holds the potential of providing comprehensive and long-term continuous analysis of sweat lactate trends in the human body during rest and under exercising conditions.}, journal={ACS SENSORS}, publisher={American Chemical Society (ACS)}, author={Saha, Tamoghna and Songkakul, Tanner and Knisely, Charles T. and Yokus, Murat A. and Daniele, Michael A. and Dickey, Michael D. and Bozkurt, Alper and Velev, Orlin D.}, year={2022}, month={Jul} }
 @article{saha_fang_yokus_mukherjee_bozkurt_daniele_dickey_velev_2021, title={A Wearable Patch for Prolonged Sweat Lactate Harvesting and Sensing}, ISSN={["1558-4615"]}, DOI={10.1109/EMBC46164.2021.9630881}, abstractNote={Operating at low sweat rates, such as those experienced by humans at rest, is still an unmet need for state-of-the-art wearable sweat harvesting and testing devices for lactate. Here, we report the on-skin performance of a non-invasive wearable sweat sampling patch that can harvest sweat at rest, during exercise, and post-exercise. The patch simultaneously uses osmosis and evaporation for long-term (several hours) sampling of sweat. Osmotic sweat withdrawal is achieved by skin-interfacing a hydrogel containing a concentrated solute. The gel interfaces with a paper strip that transports the fluid via wicking and evaporation. Proof of concept results show that the patch was able to sample sweat during resting and post-exercise conditions, where the lactate concentration was successfully quantified. The patch detected the increase in sweat lactate levels during medium level exercise. Blood lactate remained invariant with exercise as expected. We also developed a continuous sensing version of the patch by including enzymatic electrochemical sensors. Such a battery-free, passive, wearable sweat sampling patch can potentially provide useful information about the human metabolic activity.}, journal={2021 43RD ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE & BIOLOGY SOCIETY (EMBC)}, author={Saha, Tamoghna and Fang, Jennifer and Yokus, Murat A. and Mukherjee, Sneha and Bozkurt, Alper and Daniele, Michael A. and Dickey, Michael D. and Velev, Orlin D.}, year={2021}, pages={6863–6866} }
 @article{latif_dieffenderfer_tanneeru_lee_misra_bozkurt_2021, title={Evaluation of Environmental Enclosures for Effective Ambient Ozone Sensing in Wrist-worn Health and Exposure Trackers}, ISSN={["1930-0395"]}, DOI={10.1109/SENSORS47087.2021.9639530}, abstractNote={The ambient environmental conditions, most notably ozone concentration, play a critical role in exacerbating asthma related symptoms. Wearable devices offer a great potential for asthma care and management by tracking health and environmental status. Wearable devices in the form factor of a wristband using ultra-low power ozone sensors can provide a localized, real-time, and vigilant monitoring of users’ ambient environment. This work presents a preliminary investigation of environmental enclosures for such a custom designed wrist-worn wearable device for asthma. Enclosure design plays an important role in ensuring optimal environmental and gas sensor operation. In this study, we studied openings along the sidewall of the wrist-worn device covered with commercially available expanded polytetrafluoroethylene-based membranes to provide the required air flow while ensuring resistance to water.}, journal={2021 IEEE SENSORS}, author={Latif, Tahmid and Dieffenderfer, James and Tanneeru, Akhilesh and Lee, Bongmook and Misra, Veena and Bozkurt, Alper}, year={2021} }
 @article{abdelkhalek_qiu_hernandez_bozkurt_lobaton_2021, title={Investigating the Relationship between Cough Detection and Sampling Frequency for Wearable Devices}, ISSN={["1558-4615"]}, url={http://dx.doi.org/10.1109/embc46164.2021.9630082}, DOI={10.1109/EMBC46164.2021.9630082}, abstractNote={Cough detection can provide an important marker to monitor chronic respiratory conditions. However, manual techniques which require human expertise to count coughs are both expensive and time-consuming. Recent Automatic Cough Detection Algorithms (ACDAs) have shown promise to meet clinical monitoring requirements, but only in recent years they have made their way to non-clinical settings due to the required portability of sensing technologies and the extended duration of data recording. More precisely, these ACDAs operate at high sampling frequencies, which leads to high power consumption and computing requirements, making these difficult to implement on a wearable device. Additionally, reproducibility of their performance is essential. Unfortunately, as the majority of ACDAs were developed using private clinical data, it is difficult to reproduce their results. We, hereby, present an ACDA that meets clinical monitoring requirements and reliably operates at a low sampling frequency. This ACDA is implemented using a convolutional neural network (CNN), and publicly available data. It achieves a sensitivity of 92.7%, a specificity of 92.3%, and an accuracy of 92.5% using a sampling frequency of just 750 Hz. We also show that a low sampling frequency allows us to preserve patients’ privacy by obfuscating their speech, and we analyze the trade-off between speech obfuscation for privacy and cough detection accuracy.Clinical relevance—This paper presents a new cough detection technique and preliminary analysis on the trade-off between detection accuracy and obfuscation of speech for privacy. These findings indicate that, using a publicly available dataset, we can sample signals at 750 Hz while still maintaining a sensitivity above 90%, suggested to be sufficient for clinical monitoring [1].}, journal={2021 43RD ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE & BIOLOGY SOCIETY (EMBC)}, publisher={IEEE}, author={Abdelkhalek, Mahmoud and Qiu, Jinyi and Hernandez, Michelle and Bozkurt, Alper and Lobaton, Edgar}, year={2021}, pages={7103–7107} }
 @article{tabor_thompson_agcayazi_bozkurt_ghosh_2021, title={Melt-Extruded Sensory Fibers for Electronic Textiles}, volume={307}, ISSN={["1439-2054"]}, url={https://doi.org/10.1002/mame.202100737}, DOI={10.1002/mame.202100737}, abstractNote={Abstract Textile‐based flexible sensors are key to the development of personal wearable electronic devices and systems for a wide range of applications including physiological monitoring, communication, and entertainment. Textiles, for their many desirable characteristics and use, offer a natural interface between electronics and the human body. A wide range of fabrication techniques have been explored for textile‐based sensors; however, most are not compatible or readily adaptable to textile manufacturing processes. Here, a practical and scalable method of producing textile‐based sensory fibers using a common manufacturing technique, melt extrusion, is proposed. An overview of the fabrication method as well as the mechanical and electrical properties of the fibers is presented. Subsequently, the fibers’ ability to sense changes in pressure is studied in detail using assembled fibers. Methods to improve the sensor performance by altering the geometry of the fiber assembly are also presented. As a proof‐of‐concept demonstration, the fibers are woven into a pressure‐sensing fabric mat consisting of 64 sensing elements. The woven substrate can detect the location and level of pressure, thereby illustrating the fibers' potential use as sensors in textile structures.}, number={3}, journal={MACROMOLECULAR MATERIALS AND ENGINEERING}, publisher={Wiley}, author={Tabor, Jordan and Thompson, Brendan and Agcayazi, Talha and Bozkurt, Alper and Ghosh, Tushar K.}, year={2021}, month={Dec} }
 @article{ahmmed_holder_foster_castro_patel_torfs_bozkurt_2021, title={Noncontact Electrophysiology Monitoring Systems for Assessment of Canine-Human Interactions}, ISSN={["1930-0395"]}, url={http://dx.doi.org/10.1109/sensors47087.2021.9639748}, DOI={10.1109/SENSORS47087.2021.9639748}, abstractNote={Canine-assisted interactions have enormous potential in coping with psychological disorders and stress. It has been actively used for improving the mood of hospitalized patients, especially those suffering from chronic diseases like cancer. However, little progress has been made to enable the assessment of these interactions between the patient and the animal in a quantitative and undisruptive way. In this paper, we present a capacitively coupled biopotential recording system custom-designed for animal-human dyads. This system uses noncontact electrodes to monitor the heart rate and its variability to evaluate the physiological basis of the animal-assisted therapies. Preliminary in vivo evaluation of the system in humans and canines demonstrates promising measurement accuracy. The mean absolute error of the estimated heart rate was less than 0.25 BPM in reference to a commercial electrocardiography device. The future integration of this system into ergonomic form factors could enable a better understanding of animal-human interactions during canine-assisted therapy sessions by realizing an unobtrusive and continuous monitoring platform.}, journal={2021 IEEE SENSORS}, publisher={IEEE}, author={Ahmmed, Parvez and Holder, Timothy and Foster, Marc and Castro, Ivan D. and Patel, Aakash and Torfs, Tom and Bozkurt, Alper}, year={2021} }
 @article{ahmmed_reynolds_hamada_regmi_bozkurt_2021, title={Novel 3D-printed Electrodes for Implantable Biopotential Monitoring}, ISSN={["1558-4615"]}, url={http://dx.doi.org/10.1109/embc46164.2021.9630055}, DOI={10.1109/EMBC46164.2021.9630055}, abstractNote={A major bottleneck in the manufacturing process of a medical implant capable of biopotential measurements is the design and assembly of a conductive electrode interface. This paper presents the use of a novel 3D-printing process to integrate conductive metal surfaces on a low-temperature co-fired ceramic base to be deployed as electrodes for electrocardiography (ECG) implants for small animals. In order to fit the ECG sensing system within the size of an injectable microchip implant, the electronics along with a pin-type lithium-ion battery are inserted into a cylindrical glass tube with both ends sealed by these 3D printed composite electrode discs using biomedical epoxy. In the scope of this paper, we present a proof-of-concept in vivo experiment for recording ECG from an avian animal model under local anesthesia to verify the electrode performance. Simultaneous recording with a commercial device validated the measurements, demonstrating promising accuracy in heart rate and breathing rate monitoring. This novel technology could open avenues for the mass manufacturing of miniaturized ECG implants.Clinical relevance— A novel manufacturing process and an implantable system are presented for continuous physiological monitoring of animals to be used by veterinarians, animal scientists, and biomedical researchers with potential future applications in human health monitoring.}, journal={2021 43RD ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE & BIOLOGY SOCIETY (EMBC)}, publisher={IEEE}, author={Ahmmed, Parvez and Reynolds, James and Hamada, Shu and Regmi, Prafulla and Bozkurt, Alper}, year={2021}, pages={7120–7123} }
 @article{songkakul_peterson_daniele_bozkurt_2021, title={Preliminary Evaluation of a Solar-Powered Wristband for Continuous Multi-Modal Electrochemical Monitoring}, ISSN={["1558-4615"]}, DOI={10.1109/EMBC46164.2021.9630105}, abstractNote={Continuous, non-invasive wearable measurement of metabolic biomarkers could provide vital insight into patient condition for personalized health and wellness monitoring. We present our efforts towards developing a wearable solar-powered electrochemical platform for multimodal sweat based metabolic monitoring. This wrist-worn wearable system consists of a flexible photovoltaic cell connected to a circuit board containing ultra low power circuitry for sensor data collection, energy harvesting, and wireless data transmission, all integrated into an elastic fabric wristband. The system continuously samples amperometric, potentiometric, temperature, and motion data and wirelessly transmits these to a data aggregator. The full wearable system is 7.5 cm long and 5 cm in diameter, weighs 22 grams, and can run directly from harvested light energy. Relatively low levels of light such as residential lighting (∼200 lux) are sufficient for continuous operation of the system. Excess harvested energy is stored in a small 37 mWh lithium polymer battery. The battery can be charged in ∼14 minutes under full sunlight and can power the system for ∼8 days when fully charged. The system has an average power consumption of 176 µW. The solar-harvesting performance of the system was characterized in a variety of lighting conditions, and the amperometric and potentiometric electrochemical capabilities of the system were validated in vitro.Clinical relevance—The presented solar-powered wearable system enables continuous wireless multi-modal electrochemical monitoring for uninterrupted sensing of metabolic biomarkers in sweat while harvesting energy from indoor lighting or sunlight.}, journal={2021 43RD ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE & BIOLOGY SOCIETY (EMBC)}, author={Songkakul, Tanner and Peterson, Kaila and Daniele, Michael and Bozkurt, Alper}, year={2021}, pages={7316–7319} }
 @article{cole_bozkurt_lobaton_2021, title={Simultaneous Localization of Biobotic Insects using Inertial Data and Encounter Information}, ISSN={["1558-4615"]}, url={http://dx.doi.org/10.1109/embc46164.2021.9629542}, DOI={10.1109/EMBC46164.2021.9629542}, abstractNote={Several recent research efforts have shown that the bioelectrical stimulation of their neuro-mechanical system can control the locomotion of Madagascar hissing cockroaches (Gromphadorhina portentosa). This has opened the possibility of using these insects to explore centimeter-scale environments, such as rubble piles in urban disaster areas. We present an inertial navigation system based on machine learning modules that is capable of localizing groups of G. portentosa carrying thorax-mounted inertial measurement units. The proposed navigation system uses the agents’ encounters with one another as signals of opportunity to increase tracking accuracy. Results are shown for five agents that are operating on a planar (2D) surface in controlled laboratory conditions. Trajectory reconstruction accuracy is improved by 16% when we use encounter information for the agents, and up to 27% when we add a heuristic that corrects speed estimates via a search for an optimal speed-scaling factor.}, journal={2021 43RD ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE & BIOLOGY SOCIETY (EMBC)}, publisher={IEEE}, author={Cole, Jeremy and Bozkurt, Alper and Lobaton, Edgar}, year={2021}, pages={4649–4653} }
 @article{tabor_agcayazi_fleming_thompson_kapoor_liu_lee_huang_bozkurt_ghosh_2021, title={Textile-Based Pressure Sensors for Monitoring Prosthetic-Socket Interfaces}, volume={21}, ISSN={["1558-1748"]}, url={https://doi.org/10.1109/JSEN.2021.3053434}, DOI={10.1109/JSEN.2021.3053434}, abstractNote={Amputees are prone to experiencing discomfort when wearing their prosthetic devices. As the amputee population grows this becomes a more prevalent and pressing concern. There is a need for new prosthetic technologies to construct more comfortable and well-fitted liners and sockets. One of the well-recognized impediments to the development of new prosthetic technology is the lack of practical inner socket sensors to monitor the inner socket environment (ISE), or the region between the residual limb and the socket. Here we present a capacitive pressure sensor fabricated through a simple, and scalable sewing process using commercially available conductive yarns and textile materials. This fully-textile sensor provides a soft, flexible, and comfortable sensing system for monitoring the ISE. We provide details of our low-power sensor system capable of high-speed data collection from up to four sensor arrays. Additionally, we demonstrate two custom set-ups to test and validate the textile-based sensors in a simulated prosthetic environment. Finally, we utilize the textile-based sensors to study the ISE of a bilateral transtibial amputee. Results indicate that the textile-based sensors provide a promising potential for seamlessly monitoring the ISE.}, number={7}, journal={IEEE SENSORS JOURNAL}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Tabor, Jordan and Agcayazi, Talha and Fleming, Aaron and Thompson, Brendan and Kapoor, Ashish and Liu, Ming and Lee, Michael Y. and Huang, He and Bozkurt, Alper and Ghosh, Tushar K.}, year={2021}, month={Apr}, pages={9413–9422} }
 @article{martin_reynolds_daniele_lobaton_bozkurt_2021, title={Towards Continuous Plant Bioimpedance Fitting and Parameter Estimation}, ISSN={["1930-0395"]}, url={http://dx.doi.org/10.1109/sensors47087.2021.9639492}, DOI={10.1109/SENSORS47087.2021.9639492}, abstractNote={The push to advance artificial intelligence, internet of things, and big data analysis all pave the way to automated and systematic optimization in precision agriculture and smart farming applications. These advancements lead to many benefits, including the optimization of primary production, prevention of spoilage via supply chain management, and detection of crop failure risk. Noninvasive impedance sensors serve as a promising candidate for monitoring plant health wirelessly and play a major role in this optimization problem. In this study, we developed a software pipeline to support impedance sensing applications and, as a proof of concept, applied this to track longitudinal consistent bioimpedance data from the V4 leaf midrib in maize plants. The script uses the single-shell equivalent circuit model to represent the extracellular fluid, cellular membrane, and intracellular fluid as a simplified resistive-capacitive circuit, where these elements’ parameters are estimated with complex nonlinear least squares. The double-shell model extends the single-shell model to account for the effects of the relatively large plant cell vacuole. Limit cases for impedance are utilized for specific parameters as an alternative method of estimation. We investigated a complex analysis-based modification to the objective function and model optimization for the data pipeline automation. Various weighing functions are applied and checked against one another. Additionally, a custom graphical user interface was developed to assist with parameter initialization for correcting potential convergence issues and understating the influence of each parameter on the dataset. We demonstrated that the analysis of an example longitudinal dataset was able to reveal a time series for parameter fitting.}, journal={2021 IEEE SENSORS}, publisher={IEEE}, author={Martin, Devon and Reynolds, James and Daniele, Michael and Lobaton, Edgar and Bozkurt, Alper}, year={2021} }
 @article{songkakul_wu_ahmmed_reynolds_zhu_bozkurt_2021, title={Wearable Bioimpedance Hydration Monitoring System using Conformable AgNW Electrodes}, ISSN={["1930-0395"]}, url={http://dx.doi.org/10.1109/sensors47087.2021.9639469}, DOI={10.1109/SENSORS47087.2021.9639469}, abstractNote={Monitoring hydration level could be vital for maintaining physiological and cognitive performance during physical exertion and thermal stress. We present a custom miniaturized wearable bioimpedance spectroscopy (BIS) system consisting of a Bluetooth-enabled system-on-a-chip and an analog front-end circuit integrated with conformable, flexible, and stretchable silver-nanowire electrodes. This system is capable of performing four-electrode BIS at a range of frequencies between 5 kHz and 195 kHz, transmitting the data wirelessly to a data aggregator, and configuring the front-end circuit parameters over-the-air when needed. A 150 mAh lithium polymer battery can power the system for 18 hours. In this study, proof-of-concept in-vitro validation of the system generated promising results.}, journal={2021 IEEE SENSORS}, publisher={IEEE}, author={Songkakul, Tanner and Wu, Shuang and Ahmmed, Parvez and Reynolds, William D., Jr. and Zhu, Yong and Bozkurt, Alper}, year={2021} }
 @article{holder_gruen_roberts_somers_bozkurt_2020, title={A Systematic Literature Review of
Animal-Assisted Interventions in Oncology
(Part I): Methods and Results}, volume={19}, ISSN={["1552-695X"]}, DOI={10.1177/1534735420943278}, abstractNote={Animal-assisted interventions (AAIs) use human-animal interactions to positive effect in various contexts including cancer care. As the first installment of a 2-part series, this systematic literature review focuses on the research methods and quantitative results of AAI studies in oncology. We find methodological consistency in the use of canines as therapy animals, in the types of high-risk patients excluded from studies, and in the infection precautions taken with therapy animals throughout cancer wards. The investigated patient endpoints are not significantly affected by AAI, with the exceptions of improvements in oxygen consumption, quality of life, depression, mood, and satisfaction with therapy. The AAI field in oncology has progressed significantly since its inception and has great potential to positively affect future patient outcomes. To advance the field, future research should consistently improve the methodological design of studies, report data more completely, and focus more on the therapy animal’s well-being.}, journal={Integrative Cancer Therapies}, author={Holder, T. and Gruen, M. and Roberts, D. and Somers, T. and Bozkurt, A.}, year={2020}, month={Aug}, pages={1–19} }
 @misc{holder_gruen_roberts_somers_bozkurt_2020, title={A Systematic Literature Review of Animal-Assisted Interventions in Oncology (Part II): Theoretical Mechanisms and Frameworks}, volume={19}, ISSN={["1552-695X"]}, DOI={10.1177/1534735420943269}, abstractNote={Animal-assisted interventions (AAIs) can improve patients’ quality of life as complementary medical treatments. Part I of this 2-paper systematic review focused on the methods and results of cancer-related AAIs; Part II discusses the theories of the field’s investigators. Researchers cite animal personality, physical touch, physical movement, distraction, and increased human interaction as sources of observed positive outcomes. These mechanisms then group under theoretical frameworks such as the social support hypothesis or the human-animal bond concept to fully explain AAI in oncology. The cognitive activation theory of stress, the science of unitary human beings, and the self-object hypothesis are additional frameworks mentioned by some researchers. We also discuss concepts of neurobiological transduction connecting mechanisms to AAI benefits. Future researchers should base study design on theories with testable hypotheses and use consistent terminology to report results. This review aids progress toward a unified theoretical framework and toward more holistic cancer treatments.}, journal={INTEGRATIVE CANCER THERAPIES}, author={Holder, Timothy R. N. and Gruen, Margaret E. and Roberts, David L. and Somers, Tamara and Bozkurt, Alper}, year={2020}, month={Jul} }
 @article{cevik_bozkurt_dirican_zhang_2020, title={High performance flexible supercapacitors including redox active molybdate incorporated Poly(vinylphosphonic acid) hydrogels}, volume={45}, ISSN={["1879-3487"]}, DOI={10.1016/j.ijhydene.2019.11.025}, abstractNote={Novel gel polymer electrolyte (hydrogel) was prepared by incorporation of poly (vinylphosphonic acid) (PVPA) as a host matrix and redox active ammonium molybdate, Mo. Supercapacitors including active carbon electrodes were fabricated using hydrogels, PVPA/MoX where X represents the percent fraction of Mo in PVPA. All the electrolytes were in gel form and show excellent bending and stretching properties in a device. The electrochemical performance of the devices was investigated by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) experiments. Surprisingly, the specific capacitance (Cs) of the device increased to 1276 F g−1 which is at least 50 times enhancement by introducing Mo as mediator compared to the PVPA based system. The supercapacitor with PVPA/Mo10 has the highest energy density of 180.2 Wh kg−1 at a power density of 500 W kg−1. The device with the same hydrogel structure exhibited higher performance after 2300 charge-discharge cycles and the maintained 85% of its initial capacitance performance. A supercapacitor was fabricated using PVPA/Mo10 and tested under bent and twisted conditions confirming remarkable capacitance retention.}, number={3}, journal={INTERNATIONAL JOURNAL OF HYDROGEN ENERGY}, author={Cevik, E. and Bozkurt, A. and Dirican, M. and Zhang, X.}, year={2020}, month={Jan}, pages={2186–2194} }
 @article{valero-sarmiento_ahmmed_bozkurt_2020, title={In Vivo Evaluation of a Subcutaneously Injectable Implant with a Low-Power Photoplethysmography ASIC for Animal Monitoring}, volume={20}, ISSN={["1424-8220"]}, url={https://doi.org/10.3390/s20247335}, DOI={10.3390/s20247335}, abstractNote={Photoplethysmography is an extensively-used, portable, and noninvasive technique for measuring vital parameters such as heart rate, respiration rate, and blood pressure. The deployment of this technology in veterinary medicine has been hindered by the challenges in effective transmission of light presented by the thick layer of skin and fur of the animal. We propose an injectable capsule system to circumvent these limitations by accessing the subcutaneous tissue to enable reliable signal acquisition even with lower light brightness. In addition to the reduction of power usage, the injection of the capsule offers a less invasive alternative to surgical implantation. Our current prototype combines two application-specific integrated circuits (ASICs) with a microcontroller and interfaces with a commercial light emitting diode (LED) and photodetector pair. These ASICs implement a signal-conditioning analog front end circuit and a frequency-shift keying (FSK) transmitter respectively. The small footprint of the ASICs is the key in the integration of the complete system inside a 40-mm long glass tube with an inner diameter of 4 mm, which enables its injection using a custom syringe similar to the ones used with microchip implants for animal identification. The recorded data is transferred wirelessly to a computer for post-processing by means of the integrated FSK transmitter and a software-defined radio. Our optimized LED duty cycle of 0.4% at a sampling rate of 200 Hz minimizes the contribution of the LED driver (only 0.8 mW including the front-end circuitry) to the total power consumption of the system. This will allow longer recording periods between the charging cycles of the batteries, which is critical given the very limited space inside the capsule. In this work, we demonstrate the wireless operation of the injectable system with a human subject holding the sensor between the fingers and the in vivo functionality of the subcutaneous sensing on a pilot study performed on anesthetized rat subjects.}, number={24}, journal={SENSORS}, author={Valero-Sarmiento, Jose Manuel F. and Ahmmed, Parvez and Bozkurt, Alper}, year={2020}, month={Dec} }
 @article{cole_bozkurt_lobaton_2020, title={Localization of Biobotic Insects Using Low-Cost Inertial Measurement Units}, volume={20}, ISSN={["1424-8220"]}, url={https://doi.org/10.3390/s20164486}, DOI={10.3390/s20164486}, abstractNote={Disaster robotics is a growing field that is concerned with the design and development of robots for disaster response and disaster recovery. These robots assist first responders by performing tasks that are impractical or impossible for humans. Unfortunately, current disaster robots usually lack the maneuverability to efficiently traverse these areas, which often necessitate extreme navigational capabilities, such as centimeter-scale clearance. Recent work has shown that it is possible to control the locomotion of insects such as the Madagascar hissing cockroach (Gromphadorhina portentosa) through bioelectrical stimulation of their neuro-mechanical system. This provides access to a novel agent that can traverse areas that are inaccessible to traditional robots. In this paper, we present a data-driven inertial navigation system that is capable of localizing cockroaches in areas where GPS is not available. We pose the navigation problem as a two-point boundary-value problem where the goal is to reconstruct a cockroach’s trajectory between the starting and ending states, which are assumed to be known. We validated our technique using nine trials that were conducted in a circular arena using a biobotic agent equipped with a thorax-mounted, low-cost inertial measurement unit. Results show that we can achieve centimeter-level accuracy. This is accomplished by estimating the cockroach’s velocity—using regression models that have been trained to estimate the speed and heading from the inertial signals themselves—and solving an optimization problem so that the boundary-value constraints are satisfied.}, number={16}, journal={SENSORS}, publisher={MDPI AG}, author={Cole, Jeremy and Bozkurt, Alper and Lobaton, Edgar}, year={2020}, month={Aug} }
 @article{foster_brugarolas_walker_mealin_cleghern_yuschak_clark_adin_russenberger_gruen_et al._2020, title={Preliminary Evaluation of a Wearable Sensor System for Heart Rate Assessment in Guide Dog Puppies}, volume={20}, ISSN={["1558-1748"]}, url={https://doi.org/10.1109/JSEN.2020.2986159}, DOI={10.1109/JSEN.2020.2986159}, abstractNote={This paper details the development of a novel wireless heart rate sensing system for puppies in training as guide dogs. The system includes a harness with on-board electrocardiography (ECG) front-end circuit, inertial measurement unit and a micro-computer with wireless capability where the major research focus of this paper was on the ergonomic design and evaluation of the system on puppies. The first phase of our evaluation was performed on a Labrador Retriever between 12 to 26 weeks in age as a pilot study. The longitudinal weekly data collected revealed the expected trend of a decreasing average heart rate and increased heart rate variability as the age increased. In the second phase, we improved the system ergonomics for a larger scale deployment in a guide dog school (Guiding Eyes for the Blind (Guiding Eyes)) on seventy 7.5-week-old puppies (heart rate coverage average of 86.7%). The acquired ECG based heart rate data was used to predict the performance of puppies in Guiding Eyes’s temperament test. We used the data as an input to a machine learning model which predicted two Behavior Checklist (BCL) scores as determined by expert Guiding Eyes puppy evaluators with an accuracy above 90%.}, number={16}, journal={IEEE SENSORS JOURNAL}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Foster, Marc and Brugarolas, Rita and Walker, Katherine and Mealin, Sean and Cleghern, Zach and Yuschak, Sherrie and Clark, Julia Condit and Adin, Darcy and Russenberger, Jane and Gruen, Margaret and et al.}, year={2020}, pages={9449–9459} }
 @article{yokus_songkakul_pozdin_bozkurt_daniele_2020, title={Wearable multiplexed biosensor system toward continuous monitoring of metabolites}, volume={153}, ISSN={["1873-4235"]}, DOI={10.1016/j.bios.2020.112038}, abstractNote={Comprehensive metabolic panels are the most reliable and common methods for monitoring general physiology in clinical healthcare. Translation of this clinical practice to personal health and wellness tracking requires reliable, non-invasive, miniaturized, ambulatory, and inexpensive systems for continuous measurement of biochemical analytes. We report the design and characterization of a wearable system with a flexible sensor array for non-invasive and continuous monitoring of human biochemistry. The system includes signal conditioning, processing, and transmission parts for continuous measurement of glucose, lactate, pH, and temperature. The system can operate three discrete electrochemical cells. The system draws 15 mA under continuous operation when powered by a 3.7 V 150 mAh battery. The analog front-end of the electrochemical cells has four potentiostats and three multiplexers for multiplexed and parallel readout from twelve working electrodes. Utilization of redundant working electrodes improves the measurement accuracy of sensors by averaging chronoamperometric responses across the array. The operation of the system is demonstrated in vitro by simultaneous measurement of glucose and lactate, pH, and skin temperature. In benchtop measurements, the sensors are shown to have sensitivities of 26.31 μA mM-1·cm-2 for glucose, 1.49 μA mM-1·cm-2 for lactate, 54 mV·pH-1 for pH, and 0.002 °C-1 for temperature. With the custom wearable system, these values were 0.84 ± 0.03 mV μM-1·cm-2 or glucose, 31.87 ± 9.03 mV mM-1·cm-2 for lactate, 57.18 ± 1.43 mV·pH-1 for pH, and 63.4 μV·°C-1 for temperature. This miniaturized wearable system enables future evaluation of temporal changes of the sweat biomarkers.}, journal={BIOSENSORS & BIOELECTRONICS}, author={Yokus, Murat A. and Songkakul, Tanner and Pozdin, Vladimir A. and Bozkurt, Alper and Daniele, Michael A.}, year={2020}, month={Apr} }
 @article{starliper_mohammadzadeh_songkakul_hernandez_bozkurt_lobaton_2019, title={Activity-Aware Wearable System for Power-Efficient Prediction of Physiological Responses}, volume={19}, ISSN={["1424-8220"]}, url={https://doi.org/10.3390/s19030441}, DOI={10.3390/s19030441}, abstractNote={Wearable health monitoring has emerged as a promising solution to the growing need for remote health assessment and growing demand for personalized preventative care and wellness management. Vital signs can be monitored and alerts can be made when anomalies are detected, potentially improving patient outcomes. One major challenge for the use of wearable health devices is their energy efficiency and battery-lifetime, which motivates the recent efforts towards the development of self-powered wearable devices. This article proposes a method for context aware dynamic sensor selection for power optimized physiological prediction using multi-modal wearable data streams. We first cluster the data by physical activity using the accelerometer data, and then fit a group lasso model to each activity cluster. We find the optimal reduced set of groups of sensor features, in turn reducing power usage by duty cycling these and optimizing prediction accuracy. We show that using activity state-based contextual information increases accuracy while decreasing power usage. We also show that the reduced feature set can be used in other regression models increasing accuracy and decreasing energy burden. We demonstrate the potential reduction in power usage using a custom-designed multi-modal wearable system prototype.}, number={3}, journal={SENSORS}, author={Starliper, Nathan and Mohammadzadeh, Farrokh and Songkakul, Tanner and Hernandez, Michelle and Bozkurt, Alper and Lobaton, Edgar}, year={2019}, month={Feb} }
 @article{reynolds_ahmmed_bozkurt_2019, title={An Injectable System for Subcutaneous Photoplethysmography, Accelerometry, and Thermometry in Animals}, volume={13}, ISSN={["1940-9990"]}, url={http://dx.doi.org/10.1109/tbcas.2019.2923153}, DOI={10.1109/TBCAS.2019.2923153}, abstractNote={Obtaining physiological data from animals in a non-obtrusive and continuous manner is important to veterinary science. This paper demonstrates the design and deployment of a miniaturized capsule-based system for subdermal injection to provide real-time and continuous heart-rate, movement, and core-body-temperature measurements. The presented device incorporates sensors for photoplethysmography, motion detection, and temperature measurements. A bluetooth-low-energy enabled microcontroller configures the sensors, digitizes the sensor information, and wirelessly connects with external devices. The device is powered by a CR425 battery for this paper, and various other battery solutions are available based upon the use case. The design uses only commercially available integrated circuits in order to reduce the development cost and be modular. The encapsulation is a combination of medical epoxy and poly(methyl methacrylate) that fits within a 6-gauge hypodermic needle. The preliminary evaluation of the device included an in vitro assessment of its thermal response and measurement accuracy, the impact of one-month implantation on surrounding tissue, the power consumption with duty cycling of various sensors, and a measurement of physiological signals in a rat and a chicken. Having a form factor and implantation method similar to existing devices for animals, this novel system is a useful platform for both scientists and veterinarians to better study a diverse range of animals.}, number={5}, journal={IEEE TRANSACTIONS ON BIOMEDICAL CIRCUITS AND SYSTEMS}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Reynolds, James and Ahmmed, Parvez and Bozkurt, Alper}, year={2019}, month={Oct}, pages={825–834} }
 @article{agcayazi_foster_kausche_gordon_bozkurt_2019, title={Multi-axis stress sensor characterization and testing platform}, volume={5}, ISSN={2468-0672}, url={http://dx.doi.org/10.1016/J.OHX.2018.E00048}, DOI={10.1016/J.OHX.2018.E00048}, abstractNote={Multi-axis mechanical stress sensors have become an important tool in numerous fields. To characterize the quality and resolution of a new stress sensor, researchers use test platforms to apply controlled amounts of shear and normal stresses. Since commercially available multi-axis test platforms are expensive, in many cases researchers end up needing to build their own sensor characterization platforms. In this study, we describe a cost-effective multi-axis stress sensor characterization platform to reduce development time, enable accurate benchmarking and provide an open source standard for stress sensor characterization for other researchers. In our design, we combined a 3-axis translational stage and a 3-axis force and torque (F/T) sensor through custom hardware and software. Our platform is cost effective and can reach the limits of the F/T sensor (Fxy = ±65 N and Fz = ±200 N) without losing any accuracy to structural bending. We provide detailed construction and operation instructions as well as results of extensive static and cyclic load experiments. To further validate our system, we show characterization results from a custom stress sensor as a case study. The modular nature of our platform also enables other researchers to customize this characterization platform for their unique experimental requirements.}, journal={HardwareX}, publisher={Elsevier BV}, author={Agcayazi, Talha and Foster, Marc and Kausche, Hannah and Gordon, Max and Bozkurt, Alper}, year={2019}, month={Apr}, pages={e00048} }
 @article{brugarolas_yuschak_adin_roberts_sherman_bozkurt_2019, title={Simultaneous Monitoring of Canine Heart Rate and Respiratory Patterns During Scent Detection Tasks}, volume={19}, ISSN={["1558-1748"]}, DOI={10.1109/JSEN.2018.2883066}, abstractNote={Man-made technological odor detection systems continue to improve but still cannot match the tracking efficiency, mobility, and selectivity in the presence of interfering odors achieved by detector dogs. The reliability of dogs as olfactory detectors does not depend solely on their performance but also on the handler’s skill in interpreting the behavior of the dog that signals the detection of the target odor. We present our efforts on a wireless wearable system combining electrocardiogram (ECG) and an electronic stethoscope for direct monitoring of cardiopulmonary events in dogs toward enabling cybernetic dog–machine interfaces. This is, to our knowledge, the first cyber-physical attempt to simultaneously record heart rate, heart rate variability, and continuous auscultation of respiratory behavior in a wearable form factor during scent-detection tasks. In this paper, we present: 1) a method to automate the detection of sniffing episodes based on power spectral density of the respiratory sounds; 2) proof-of-concept extraction and quantification of the ECG and respiratory sounds features that would enable the discovery of physiological patterns associated to scent-detection tasks; and 3) proof-of-concept correlation of such patterns with the presence/absence of target odors. These contributions pave the way for a novel real-time cybernetic olfactory detection monitoring system to provide decision support for handlers in the field in addition to enabling future computer-sniffing dog interfaces.}, number={4}, journal={IEEE SENSORS JOURNAL}, author={Brugarolas, Rita and Yuschak, Sherrie and Adin, Darcy and Roberts, David L. and Sherman, Barbara L. and Bozkurt, Alper}, year={2019}, month={Feb}, pages={1454–1462} }
 @inbook{mcknight_agcayazi_ghosh_bozkurt_2018, title={Fiber-Based Sensors: Enabling Next Generation Ubiquitous Textile Systems.}, ISBN={9780128118108}, url={http://dx.doi.org/10.1016/b978-0-12-811810-8.00008-7}, DOI={10.1016/b978-0-12-811810-8.00008-7}, abstractNote={One of the grand challenges of producing truly ubiquitous textile wearable systems is the development of sensors, actuators, and interconnects, which can be seamlessly integrated into textiles using traditional textile manufacturing techniques while not disrupting the primary functions of clothing, for example, comfort. In order to be adapted on a large-scale within the textile industries, such components should be compatible with traditional textile materials (fibers, yarns, and fabric) in physical and mechanical properties, and would ideally be produced using conventional textile processing methods. The development of a fiber capable of sensing multiple parameters enables facile integration of sensing elements into textile substrates, which can provide spatial sensor information across the surface of a textile. Additionally, sensing fibers and fabrics can be tailored to sense different parameters of interest at different locations within a textile. Prior work has demonstrated that fiber-based sensors produced using microfabrication techniques, screen printing, and 3D printing methods can enable sensing of multiple physiological parameters including biopotentials, pressure, and wetness. Here, we also discuss other sensing methods, which could be implemented using fibers and fibrous structures, and explore the challenges to producing such devices/systems such that they are robust enough for use in textile applications.}, booktitle={Wearable Technology in Medicine and Health Care}, publisher={Elsevier}, author={McKnight, Michael and Agcayazi, Talha and Ghosh, Tushar and Bozkurt, Alper}, editor={Tong, RaymondEditor}, year={2018}, pages={153–171} }
 @misc{agcayazi_chatterjee_bozkurt_ghosh_2018, title={Flexible Interconnects for Electronic Textiles}, volume={3}, ISSN={["2365-709X"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85041134838&partnerID=MN8TOARS}, DOI={10.1002/admt.201700277}, abstractNote={Conformable electrical systems integrated in textiles offer revolutionary possibilities. Textiles constitute an obvious choice as a multifunctional electronic platform, since they are worn and used to cover many surfaces around us. The primary focus of the emerging area of electronic textiles (e‐textiles) is on developing transformative technologies to produce flexible, conformable, and large‐area textile‐based electronic systems. One of the main roadblocks to development of e‐textiles is making (fiber‐to‐fiber) interconnects within textiles, with rigid semiconductor‐based circuits and other devices, and efficiently routing these circuits. This problem is compounded by the need for the textile and other materials to withstand the stresses and strains of manufacturing and end‐use. The fundamental challenge of forming these interconnects involves making them flexible, robust, and environmentally stable while ensuring adequate electrical connectivity. From a mechanical standpoint, the transition from soft to hard materials should occur with minimum stress/strain concentration. These challenges, if unaddressed, will remain a barrier to large‐scale development of textile‐based electronic systems. This work reviews the technological issues related to the textile interconnect, providing an overview of flexible interconnects, including relevant materials, electrical and mechanical characterization techniques, ways of forming flexible conductive pathways, and potential research directions and challenges.}, number={10}, journal={ADVANCED MATERIALS TECHNOLOGIES}, author={Agcayazi, Talha and Chatterjee, Kony and Bozkurt, Alper and Ghosh, Tushar K.}, year={2018}, month={Oct} }
 @article{valero-sarmiento_reynolds_krystal_bozkurt_2018, title={In Vitro</italic> Evaluation of an Injectable EEG/ECG Sensor for Wireless Monitoring of Hibernation in Endangered Animal Species}, volume={18}, ISSN={1530-437X 1558-1748 2379-9153}, url={http://dx.doi.org/10.1109/jsen.2017.2772844}, DOI={10.1109/jsen.2017.2772844}, abstractNote={Hibernation is a unique metabolic adaptation employed by several animal species for survival where its study would further enhance our understanding of metabolic disorders, such as diabetes and obesity. As a primate animal with close genetic ties to humans, the recent discovery of hibernation in dwarf lemurs of Madagascar has attracted the attention of researchers. Traditional recording systems require the physical tethering of the animals to the recording apparatus or the use of implantable devices. Scalp and needle electrodes interfere with the natural hibernation process and limit the continuity of the experiments, while invasive procedures are banned on endangered species. By integrating a full-wave rectifier, low-noise signal conditioning circuit, frequency modulation transmitter, and antenna in a single application specific integrated circuit (ASIC), we have developed an ultra-miniaturized wireless system that measures <inline-formula> <tex-math notation="LaTeX">$34 \times 4 \times 2.6$ </tex-math></inline-formula> mm<sup>3</sup> in volume. It only requires three off-chip components (a coil wound around a ferrite rod and two external capacitors) to be powered wirelessly through a 1-MHz inductive link, such that it can be packaged inside a glass or polymer capsule and injected subcutaneously underneath the scalp or chest without requiring a surgery, thereby addressing the shortcomings of the traditional monitoring systems. Our recording device provides an input/output correlation coefficient greater than 80% for input amplitudes ranging from 60 to 260 <inline-formula> <tex-math notation="LaTeX">$\mu V_{\mathrm{ pp}}$ </tex-math></inline-formula>, with a wireless data transmission range of ~2.5 cm while operating near the 902–928 MHz ISM frequency band. This system would enable future studies of electroencephalography and electrocardiography in hibernating dwarf lemurs. The ASIC was fabricated using the ON Semiconductor 0.5-<inline-formula> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> CMOS process with an active area of 2.5 <inline-formula> <tex-math notation="LaTeX">$\times $ </tex-math></inline-formula> 1 mm<sup>2</sup> and has a power consumption of 7.75 mW from a 3.1 V supply. In this paper, we demonstrate the <italic>in vitro</italic> functionality of the system using simulated physiological signals directly applied to the ASIC or through standard stainless steel electrodes immersed in saline solution.}, number={2}, journal={IEEE Sensors Journal}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Valero-Sarmiento, Jose Manuel and Reynolds, James and Krystal, Andrew and Bozkurt, Alper}, year={2018}, month={Jan}, pages={798–808} }
 @article{latif_mcknight_dickey_bozkurt_2018, title={In vitro electrochemical assessment of electrodes for neurostimulation in roach biobots}, volume={13}, ISSN={["1932-6203"]}, DOI={10.1371/journal.pone.0203880}, abstractNote={Biobotics investigates the use of live insects as biological robots whose locomotion can be controlled by neurostimulation through implanted electrodes. Inactivity in the biobots (biological robots) can sometimes be noticed following extended neurostimulation, partly owing to incompatibility of implanted electrodes with the biobotic application or gradual degradation of the tissue-electrode interface. Implanted electrodes need to sufficiently exhibit consistent, reliable, and stable performance during stimulation experiments, have low tissue-electrode impedance, facilitate good charge injection capacity, and be compact in size or shape. Towards the goal of finding such electrodes suitable for biobotic applications, we compare electrochemical performances of five different types of electrodes in vitro with a saline based electrolytic medium. These include stainless steel wire electrodes, microfabricated flexible gold electrodes coated with PEDOT:PSS conductive polymer, eutectic gallium indium (EGaIn) in a tube, and “hybrid” stainless steel electrodes coated with EGaIn. We also performed accelerated aging of the electrodes to help estimate their longitudinal performance. Based on our experimentation, microfabricated electrodes with PEDOT:PSS and stainless steel electrodes coated with EGaIn performed remarkably well. This is the first time conductive polymer and liquid metal electrodes were studied comparatively for neurostimulation applications. These in vitro comparison results will be used in the future to provide a benchmark for subsequent in vivo tests with implanted electrodes in cockroach biobots.}, number={10}, journal={PLOS ONE}, publisher={Public Library of Science (PLoS)}, author={Latif, Tahmid and McKnight, Michael and Dickey, Michael D. and Bozkurt, Alper}, editor={Lebedev, NikolaiEditor}, year={2018}, month={Oct} }
 @article{kapoor_mcknight_chatterjee_agcayazi_kausche_bozkurt_ghosh_2018, title={Toward Fully Manufacturable, Fiber Assembly-Based Concurrent Multimodal and Multifunctional Sensors for e-Textiles}, volume={4}, ISSN={2365-709X}, url={http://dx.doi.org/10.1002/ADMT.201800281}, DOI={10.1002/ADMT.201800281}, abstractNote={Soft polymer‐based sensors as an integral part of textile structures have attracted considerable scientific and commercial interest recently because of their potential use in healthcare, security systems, and other areas. While electronic sensing functionalities can be incorporated into textiles at one or more of the hierarchical levels of molecules, fibers, yarns, or fabrics, arguably a more practical and inconspicuous means to introduce the desired electrical characteristics is at the fiber level, using processes that are compatible to textiles. Here, a prototype multimodal and multifunctional sensor array formed within a woven fabric structure using bicomponent fibers with ordered insulating and conducting segments is reported. The multifunctional characteristics of the sensors are successfully demonstrated by measuring tactile, tensile, and shear deformations, as well as wetness and biopotential. While the unobtrusive integration of sensing capabilities offers possibilities to preserve all desirable textile qualities, this scaled‐up fiber‐based approach demonstrates the potential for scalable and facile manufacturability of practical e‐textile products using low‐cost roll‐to‐roll processing of large‐area flexible sensor systems and can be remarkably effective in advancing the field of e‐textiles.}, number={1}, journal={Advanced Materials Technologies}, publisher={Wiley}, author={Kapoor, Ashish and McKnight, Michael and Chatterjee, Kony and Agcayazi, Talha and Kausche, Hannah and Bozkurt, Alper and Ghosh, Tushar K.}, year={2018}, month={Oct}, pages={1800281} }
 @article{pamula_valero-sarmiento_yan_bozkurt_van hoof_van helleputte_yazicioglu_verhelst_2017, title={A 172 mu W Compressively Sampled Photoplethysmographic (PPG) Readout ASIC With Heart Rate Estimation Directly From Compressively Sampled Data}, volume={11}, ISSN={["1940-9990"]}, DOI={10.1109/tbcas.2017.2661701}, abstractNote={A compressive sampling (CS) photoplethysmographic (PPG) readout with embedded feature extraction to estimate heart rate (HR) directly from compressively sampled data is presented. It integrates a low-power analog front end together with a digital back end to perform feature extraction to estimate the average HR over a 4 s interval directly from compressively sampled PPG data. The application-specified integrated circuit (ASIC) supports uniform sampling mode (1x compression) as well as CS modes with compression ratios of 8x, 10x, and 30x. CS is performed through nonuniformly subsampling the PPG signal, while feature extraction is performed using least square spectral fitting through Lomb–Scargle periodogram. The ASIC consumes 172 $\mu$ W of power from a 1.2 V supply while reducing the relative LED driver power consumption by up to 30 times without significant loss of relevant information for accurate HR estimation.}, number={3}, journal={IEEE TRANSACTIONS ON BIOMEDICAL CIRCUITS AND SYSTEMS}, author={Pamula, Venkata Rajesh and Valero-Sarmiento, Jose Manuel and Yan, Long and Bozkurt, Alper and Van Hoof, Chris and Van Helleputte, Nick and Yazicioglu, Refet Firat and Verhelst, Marian}, year={2017}, month={Jun}, pages={487–496} }
 @article{yao_myers_malhotra_lin_bozkurt_muth_zhu_2017, title={A Wearable Hydration Sensor with Conformal Nanowire Electrodes}, volume={6}, ISSN={2192-2640}, url={http://dx.doi.org/10.1002/ADHM.201601159}, DOI={10.1002/ADHM.201601159}, abstractNote={A wearable skin hydration sensor in the form of a capacitor is demonstrated based on skin impedance measurement. The capacitor consists of two interdigitated or parallel electrodes that are made of silver nanowires (AgNWs) in a polydimethylsiloxane (PDMS) matrix. The flexible and stretchable nature of the AgNW/PDMS electrode allows conformal contact to the skin. The hydration sensor is insensitive to the external humidity change and is calibrated against a commercial skin hydration system on an artificial skin over a wide hydration range. The hydration sensor is packaged into a flexible wristband, together with a network analyzer chip, a button cell battery, and an ultralow power microprocessor with Bluetooth. In addition, a chest patch consisting of a strain sensor, three electrocardiography electrodes, and a skin hydration sensor is developed for multimodal sensing. The wearable wristband and chest patch may be used for low‐cost, wireless, and continuous monitoring of skin hydration and other health parameters.}, number={6}, journal={Advanced Healthcare Materials}, publisher={Wiley}, author={Yao, Shanshan and Myers, Amanda and Malhotra, Abhishek and Lin, Feiyan and Bozkurt, Alper and Muth, John F. and Zhu, Yong}, year={2017}, month={Jan}, pages={1601159} }
 @article{dirafzoon_bozkurt_lobaton_2017, title={A framework for mapping with biobotic insect networks: From local to global maps}, volume={88}, url={http://dx.doi.org/10.1016/j.robot.2016.11.004}, DOI={10.1016/j.robot.2016.11.004}, abstractNote={We present an approach for global exploration and mapping of unknown environments using a swarm of cyborg insects, known as biobots, for emergency response scenarios under minimal sensing and localization constraints. We exploit natural stochastic motion models and controlled locomotion of biobots in conjunction with an aerial leader to explore and map a domain of interest. A sliding window strategy is adopted to construct local maps from coordinate free encounter information of the agents by means of local metric estimation. Robust topological features from these local representations are extracted using topological data analysis and a classification scheme. These maps are then merged into a global map which can be visualized using a graphical representation, that integrates geometric as well as topological features of the environment. Simulation and experimental results with biologically inspired robotic platform are presented to illustrate and verify the correctness of our approach, which provides building blocks for SLAM with biobotic insects.}, journal={Robotics and Autonomous Systems}, publisher={Elsevier BV}, author={Dirafzoon, Alireza and Bozkurt, Alper and Lobaton, Edgar}, year={2017}, month={Feb}, pages={79–96} }
 @article{majikes_brugarolas_winters_yuschak_mealin_walker_yang_sherman_bozkurt_roberts_2017, title={Balancing noise sensitivity, response latency, and posture accuracy for a computer-assisted canine posture training system}, volume={98}, ISSN={["1095-9300"]}, DOI={10.1016/j.ijhcs.2016.04.010}, abstractNote={This paper describes a canine posture detection system composed of wearable sensors and instrumented devices that detect the postures sit, stand, and eat. The system consists of a customized harness outfitted with wearable Inertial Measurement Units (IMUs) and a base station for processing IMU data to classify canine postures. Research in operant conditioning, the science of behavior change, indicates that successful animal training requires consistent and accurate feedback on behavior. Properly designed computer systems excel at timeliness and accuracy, which are two characteristics most amateur trainers struggle with and professionals strive for. Therefore, in addition to the system being ergonomically designed to ensure the dog׳s comfort and well-being, it is engineered to provide posture detection with timing and accuracy on par with a professional trainer. We contend that providing a system with these characteristics will one day aid dogs in learning from humans by overcoming poor or ineffective timing during training. We present the initial steps in the development and validation of a computer-assisted training system designed to work outside of laboratory environments. The main contributions of this work are (a) to explore the trade-off between low-latency responses to changes in time-series IMU data representative of posture changes while maintaining accuracy and timing similar to a professional trainer, and (b) to provide a model for future ACI technologies by documenting the user-centered approach we followed to create a computer-assisted training system that met the criteria identified in (a). Accordingly, in addition to describing our system, we present the results of three experiments to characterize the performance of the system at capturing sit postures of dogs and providing timely reinforcement. These trade-offs are illustrated through the comparison of two algorithms. The first is Random Forest classification and the second is an algorithm which uses a Variance-based Threshold for classification of postures. Results indicate that with proper parameter tuning, our system can successfully capture and reinforce postures to provide computer-assisted training of dogs.}, journal={INTERNATIONAL JOURNAL OF HUMAN-COMPUTER STUDIES}, author={Majikes, John and Brugarolas, Rita and Winters, Michael and Yuschak, Sherrie and Mealin, Sean and Walker, Katherine and Yang, Pu and Sherman, Barbara and Bozkurt, Alper and Roberts, David L.}, year={2017}, month={Feb}, pages={179–195} }
 @article{dirafzoon_bozkurt_lobaton_2017, title={Geometric Learning and Topological Inference With Biobotic Networks}, volume={3}, ISSN={["2373-776X"]}, url={http://dx.doi.org/10.1109/tsipn.2016.2623093}, DOI={10.1109/tsipn.2016.2623093}, abstractNote={In this study, we present and analyze a framework for geometric and topological estimation for mapping of unknown environments. We consider agents mimicking motion behaviors of cyborg insects, known as biobots, and exploit coordinate-free local interactions among them to infer geometric and topological information about the environment, under minimal sensing and localization constraints. A metric estimation procedure is presented over a graphical representation referred to as the encounter graph in order to construct a geometric point cloud using manifold learning techniques. Topological data analysis (TDA) along with the proposed classification method is used to infer robust topological features of the space (e.g., existence of obstacles). We examine the asymptotic behavior of the proposed metric in terms of the convergence to the geodesic distances in the underlying manifold of the domain, and provide stability analysis results for the topological persistence. The proposed framework and its convergences and stability analysis are demonstrated through numerical simulations and experiments with Hexbugs.}, number={1}, journal={IEEE TRANSACTIONS ON SIGNAL AND INFORMATION PROCESSING OVER NETWORKS}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Dirafzoon, Alireza and Bozkurt, Alper and Lobaton, Edgar}, year={2017}, month={Mar}, pages={200–215} }
 @article{yao_myers_malhotra_lin_bozkurt_muth_zhu_2017, title={Hydration Sensing: A Wearable Hydration Sensor with Conformal Nanowire Electrodes (Adv. Healthcare Mater. 6/2017)}, volume={6}, ISSN={2192-2640}, url={http://dx.doi.org/10.1002/ADHM.201770031}, DOI={10.1002/adhm.201770031}, abstractNote={A wearable skin hydration sensor is developed by Y. Zhu, J. F. Muth, and co-workers in article number 1601159. The sensor is made of silver nanowires inlaid in a silicone substrate, which renders the sensor flexible and stretchable. Integrated systems with multimodal sensing capability (e.g., hydration, strain/motion and electrophysiological sensing) are demonstrated in two form factors — wristband and chest patch. Image design by Shanshan Yao.}, number={6}, journal={Advanced Healthcare Materials}, publisher={Wiley}, author={Yao, Shanshan and Myers, Amanda and Malhotra, Abhishek and Lin, Feiyan and Bozkurt, Alper and Muth, John F. and Zhu, Yong}, year={2017}, month={Mar} }
 @article{latif_bozkurt_2017, title={Roach Biobots Toward reliability and optimization of control}, volume={8}, ISSN={["2154-2287"]}, DOI={10.1109/mpul.2017.2729413}, abstractNote={Imagine a natural disaster, such as an earthquake, causing residential buildings to collapse and trapping the people inside underneath the rubble. Over the following days, first responders spend a significant amount of time locating survivors. Despite having the assistance of life-detection tools and techniques, these first responders are still hampered by certain limitations in searching for survivors and pinpointing their exact location deep within the rubble. Current methods involving dogs and relatively large robots and machinery can assist only with surface-level surveying of the disaster area and removal of rubble. In contrast, a swarm of centimeter-scale robots could be employed for under-rubble mapping and surveying in these scenarios. In fact, progress has been made in developing centimeter-scale robotics that could assist first responders in the future. However, these prototypes still require improvements in the efficiency of the mechanical parts and control systems deployed in real-life scenarios.}, number={5}, journal={IEEE PULSE}, author={Latif, Tahmid and Bozkurt, Alper}, year={2017}, pages={27–30} }
 @article{dieffenderfer_krystal_bozkurt_2017, title={Shedding Light to Sleep Studies}, volume={10352}, ISBN={["978-1-5106-1161-0"]}, ISSN={["1996-756X"]}, DOI={10.1117/12.2275625}, abstractNote={This paper presents our efforts in the development of a small wireless, flexible bandage sized near-infrared spectroscopy (NIRS) system for sleep analysis. The current size of the system is 2.8 cm × 1.7 cm × 0.6 cm. It is capable of performing NIRS with 660nm, 940nm and 850nm wavelengths for up to 11 hours continuously. The device is placed on the forehead to measure from the prefrontal cortex and the raw data is continuously streamed over Bluetooth to a nearby data aggregator such as a smartphone for post processing and cloud connection. In this study, we performed traditional polysomnography simultaneously with NIRS to evaluate agreement with traditional measures of sleep and to provide labelled data for future work involving learning algorithms. Ultimately, we expect a machine learning algorithm to be able to generate characterization of sleep states comparable to traditional methods based on this biophotonics data. The system also includes an inertial measurement unit and the features that can be extracted from the presented system include sleep posture, heart rate, respiratory rate, relative change in oxy and deoxy hemoglobin concentrations and tissue oxygenation and cerebral arterial oxygen extracted from these. Preliminary proof of concept results are promising and demonstrate the capability to measure heart rate, respiratory rate and slow-wave-sleep stages. This system serves as a prototype to evaluate the potential of a small bandage-size continuous-wave NIRS device to be a useful means of studying sleep.}, journal={BIOSENSING AND NANOMEDICINE X}, author={Dieffenderfer, James and Krystal, Andrew and Bozkurt, Alper}, year={2017} }
 @inbook{majikes_yuschak_walker_brugarolas_mealin_foster_bozkurt_sherman_roberts_2017, title={Stimulus Control for Semi-autonomous Computer Canine-Training}, ISBN={9783319635361 9783319635378}, ISSN={0302-9743 1611-3349}, url={http://dx.doi.org/10.1007/978-3-319-63537-8_24}, DOI={10.1007/978-3-319-63537-8_24}, abstractNote={For thousands of years, humans have domesticated and trained dogs to perform tasks for them. Humans have developed areas of study, such as Applied Behavior Analysis, which aim to improve the training process. We introduce a semi-autonomous, canine-training system by combining existing research in Applied Behavior Analysis with computer systems consisting of hardware, software, audio, and visual components. These components comprise a biohybrid system capable of autonomously training a dog to perform a specific behavior on command. In this paper we further our previous computer canine-training system by the application of stimulus control over a newly-acquired, free operant behavior. This system uses light and sound as a discriminative stimulus for the behavior of a dog pushing a button with its nose. Indications of simple stimulus control of this behavior were achieved. Our pilot of this system indicates canine learning comparable to that from a professional dog trainer.}, booktitle={Biomimetic and Biohybrid Systems}, publisher={Springer International Publishing}, author={Majikes, John J. and Yuschak, Sherrie and Walker, Katherine and Brugarolas, Rita and Mealin, Sean and Foster, Marc and Bozkurt, Alper and Sherman, Barbara and Roberts, David L.}, year={2017}, pages={279–290} }
 @inproceedings{rajesh_valero-sarmiento_yan_bozkurt_van hoof_van helleputte_yazicioglu_verhelst_2016, title={A 172 mu W compressive sampling photoplethysmographic readout with embedded direct heart-rate and variability extraction from compressively sampled data}, volume={59}, booktitle={2016 ieee international solid-state circuits conference (isscc)}, author={Rajesh, P. V. and Valero-Sarmiento, J. M. and Yan, L. and Bozkurt, A. and Van Hoof, C. and Van Helleputte, N. and Yazicioglu, R. F. and Verhelst, M.}, year={2016}, pages={386–541} }
 @article{bozkurt_lobaton_sichitiu_2016, title={A Biobotic Distributed Sensor Network for Under-Rubble Search and Rescue}, volume={49}, ISSN={["1558-0814"]}, url={http://dx.doi.org/10.1109/mc.2016.136}, DOI={10.1109/mc.2016.136}, abstractNote={Utilizing the latest neural engineering developments, researchers have enabled biobotic insects that function as search-and-rescue agents to help map under-rubble environments and locate survivors and hazardous conditions. The Web extra at http://youtu.be/oJXEPcv-FMw is a video in which authors Alper Bozkurt, Edgar Lobaton, and Mihail Sichitiu demonstrate the acoustic steering of roach biobots to search for disaster victims trapped under rubble.}, number={5}, journal={COMPUTER}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Bozkurt, Alper and Lobaton, Edgar and Sichitiu, Mihail}, year={2016}, month={May}, pages={38–46} }
 @inproceedings{agcayazi_mcknight_kausche_ghosh_bozkurt_2016, title={A finger touch force detection method for textile based capacitive tactile sensor arrays}, DOI={10.1109/icsens.2016.7808528}, abstractNote={The use of touch-based technology to interact with electronic devices pre-dates modern day multi-touch technology and even the personal computer. It has recently been growing in popularity in wearable computing devices especially in the form of textile based tactile sensor. These sensors often target the detection of not only touch but also force applied. A significant problem arises here in differentiating inputs from an intended finger touch and just a bend of the sensor or other objects touching the sensor. In this work, we present our initial efforts to differentiate between a finger and an insulated object touch event on a custom textile based tactile sensor we developed before. Our experiments show that the two cases could be differentiated using the capacitance change of the neighboring cross-over points.}, booktitle={2016 ieee sensors}, author={Agcayazi, T. and McKnight, M. and Kausche, H. and ghosh and Bozkurt, A.}, year={2016} }
 @inproceedings{brugarolas_valero-sarmiento_bozkurt_essick_2016, title={Auto-adjusting mandibular repositioning device for in-home use}, DOI={10.1109/embc.2016.7591677}, abstractNote={Obstructive Sleep Apnea (OSA) is a form of respiratory dysfunction that affects 20% of adults in the world. Among the first-line treatments that are used to mitigate the effects of OSA are continuous positive airway pressure (CPAP) and mandibular repositioning devices (MRD). Although CPAP provides a more efficacious therapy than MRDs, recent studies suggest that both are comparable in overall effectiveness due to greater patient preference and adherence to MRD therapy. In this paper, we present the Auto-Positioner, a novel add-on for MRDs that adjusts the extent to which the mandible (lower jaw) is advanced in response to respiratory signals indicating labored breathing during sleep, and to changes in sleeping position known to affect individual patient's airway patency.}, booktitle={2016 38th annual international conference of the ieee engineering in medicine and biology society (embc)}, author={Brugarolas, R. and Valero-Sarmiento, J. M. and Bozkurt, A. and Essick, G. K.}, year={2016}, pages={4296–4299} }
 @inproceedings{xiong_latif_lobaton_bozkurt_sichitiu_2016, title={Characterization of RSS variability for biobot localization using 802.15.4 radios}, DOI={10.1109/wisnet.2016.7444305}, abstractNote={A cyber-physically organized swarm of insect biobots or biological robots can aid first responders in search-and-rescue scenarios after natural disasters or earthquakes by establishing an under-rubble sensor network. In such a network, the nodes are represented by the insect biobots equipped with electronic backpacks utilizing a system-on-chip. This application requires effective real-time localization of the mobile sensor nodes. Radio signal strength (RSS) is a measurement of the received signal power, and can be used in estimating the distance between two nodes, which then can help localize the biobotic sensor nodes in the future. This paper investigates RSS variability and its suitability for biobotic localization.}, booktitle={2016 ieee topical conference on wireless sensors and sensor networks (wisnet)}, author={Xiong, H. and Latif, T. and Lobaton, E. and Bozkurt, A. and Sichitiu, Mihail L.}, year={2016}, pages={1–3} }
 @article{dieffenderfer_goodell_mills_mcknight_yao_lin_beppler_bent_lee_misra_et al._2016, title={Low-Power Wearable Systems for Continuous Monitoring of Environment and Health for Chronic Respiratory Disease}, volume={20}, ISSN={2168-2194 2168-2208}, url={http://dx.doi.org/10.1109/JBHI.2016.2573286}, DOI={10.1109/jbhi.2016.2573286}, abstractNote={We present our efforts toward enabling a wearable sensor system that allows for the correlation of individual environmental exposures with physiologic and subsequent adverse health responses. This system will permit a better understanding of the impact of increased ozone levels and other pollutants on chronic asthma conditions. We discuss the inefficiency of existing commercial off-the-shelf components to achieve continuous monitoring and our system-level and nano-enabled efforts toward improving the wearability and power consumption. Our system consists of a wristband, a chest patch, and a handheld spirometer. We describe our preliminary efforts to achieve a submilliwatt system ultimately powered by the energy harvested from thermal radiation and motion of the body with the primary contributions being an ultralow-power ozone sensor, an volatile organic compounds sensor, spirometer, and the integration of these and other sensors in a multimodal sensing platform. The measured environmental parameters include ambient ozone concentration, temperature, and relative humidity. Our array of sensors also assesses heart rate via photoplethysmography and electrocardiography, respiratory rate via photoplethysmography, skin impedance, three-axis acceleration, wheezing via a microphone, and expiratory airflow. The sensors on the wristband, chest patch, and spirometer consume 0.83, 0.96, and 0.01 mW, respectively. The data from each sensor are continually streamed to a peripheral data aggregation device and are subsequently transferred to a dedicated server for cloud storage. Future work includes reducing the power consumption of the system-on-chip including radio to reduce the entirety of each described system in the submilliwatt range.}, number={5}, journal={IEEE Journal of Biomedical and Health Informatics}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Dieffenderfer, James and Goodell, Henry and Mills, Steven and McKnight, Michael and Yao, Shanshan and Lin, Feiyan and Beppler, Eric and Bent, Brinnae and Lee, Bongmook and Misra, Veena and et al.}, year={2016}, month={Sep}, pages={1251–1264} }
 @inproceedings{keller_wilkins_reynolds_dieffenderfer_hood_daniele_bozkurt_tunc-ozdemir_2016, title={Nanocellulose electrodes for interfacing plant electrochemistry}, booktitle={2016 ieee sensors}, author={Keller, K. and Wilkins, M. and Reynolds, J. and Dieffenderfer, J. and Hood, C. and Daniele, M. A. and Bozkurt, A. and Tunc-Ozdemir, M.}, year={2016} }
 @inproceedings{latif_yang_lobaton_bozkurt_2016, title={Preliminary statistical assessment towards characterization of biobotic control}, booktitle={2016 38th annual international conference of the ieee engineering in medicine and biology society (embc)}, author={Latif, T. and Yang, M. and Lobaton, E. and Bozkurt, A.}, year={2016}, pages={2184–2187} }
 @inproceedings{tanneeru_mills_lim_mahmud_dieffenderfer_bozkurt_nagle_lee_misra_2016, title={Room temperature sensing of VOCS by atomic layer deposition of metal oxide}, DOI={10.1109/icsens.2016.7808786}, abstractNote={This work demonstrates room temperature sensing of volatile organic compound (VOC) — acetone via an ultrathin film metal oxide sensing layer. Atomic layer deposition (ALD) enables a high quality ultrathin film with precise thickness control. The 14nm ultrathin SnO2 thin film was deposited by ALD resulting in VOCs sensing at room temperature. The ultra-low power consumption (less than 50nW) and the room temperature operation of these devices make them compatible with wearable devices for real-time health and environment monitoring.}, booktitle={2016 ieee sensors}, author={TANNEERU, AKHILESH and Mills, S. and Lim, M. and Mahmud, M. M. and Dieffenderfer, J. and Bozkurt, A. and Nagle, T. and Lee, B. and Misra, V.}, year={2016} }
 @inproceedings{mcknight_agcayazi_kausche_ghosh_bozkurt_2016, title={Sensing textile seam-line for wearable multimodal physiological monitoring}, DOI={10.1109/embc.2016.7590702}, abstractNote={This paper investigates a novel multimodal sensing method by forming seam-lines of conductive textile fibers into commercially available fabrics. The proposed ultra-low cost micro-electro-mechanical sensor would provide, wearable, flexible, textile based biopotential signal recording, wetness detection and tactile sensing simultaneously. Three types of fibers are evaluated for their array-based sensing capability, including a 3D printed conductive fiber, a multiwall carbon nanotube based fiber, and a commercially available stainless steel conductive thread. The sensors were shown to have a correlation between capacitance and pressure; impedance and wetness; and recorded potential and ECG waveforms.}, booktitle={2016 38th annual international conference of the ieee engineering in medicine and biology society (embc)}, author={McKnight, M. and Agcayazi, T. and Kausche, H. and ghosh and Bozkurt, A.}, year={2016}, pages={311–314} }
 @inproceedings{lin_yao_mcknight_zhu_bozkurt_2016, title={Silver nanowire based wearable sensors for multimodal sensing}, DOI={10.1109/biowireless.2016.7445561}, abstractNote={We present multifunctional sensors based on highly stretchable silver nanowire conductors, which can be conformally attached to human skin for multimodal sensing. The wearable sensors were integrated with an interface circuit with wireless capability in the form of a chest patch. The capabilities of electrocardiography, strain/motion sensing and skin impedance sensing were demonstrated. Additionally, the impedance sensor with the interface circuit was packaged into a wrist watch for skin impedance monitoring.}, booktitle={Ieee topical conference on biomedical wireless technologies networks and}, author={Lin, F. Y. and Yao, S. S. and McKnight, M. and Zhu, Y. and Bozkurt, A.}, year={2016}, pages={55–58} }
 @inproceedings{majikes_mealin_rita_walker_yuschak_sherman_bozkurt_roberts_2016, title={Smart connected canines: IoT design considerations for the lab, home, and mission-critical environments (invited paper)}, DOI={10.1109/sarnof.2016.7846739}, abstractNote={The canine-human relationship continues to grow as dogs become an increasingly critical part of our society. As reliance on dogs has increased from simple companionship, to service dogs, urban security, and national defense, the opportunities for enhanced communications between the working canine and their handler increase. Wireless sensor networks and the Internet of Things (IoT) can extend traditional canine-human communication to integrate canines into the cyber-enabled world. This is what we call the Smart Connected Canine (SCC). Canine-computer interaction is sufficiently different from human-computer interaction so as to present some challenging research and design problems. There are physical and performance limits to what a dog will naturally tolerate. There are communications requirements for monitoring dogs, monitoring the environment, and for canine-human communications. Depending on the working environment there are different performance, security, and ergonomic considerations. This paper summarizes three example canine-human systems we presented earlier along with their Ion data characteristics and design criteria in order to explore how smart connected canines can improve our lives, the future of smart connected canines, and the requirements on IoT technologies to facilitate this future.}, booktitle={2016 ieee 37th sarnoff symposium}, author={Majikes, J. J. and Mealin, S. and Rita, B. and Walker, K. and Yuschak, S. and Sherman, B. and Bozkurt, A. and Roberts, D. L.}, year={2016}, pages={118–123} }
 @inproceedings{kapoor_mcknight_chatterjee_agcayazi_kausche_ghosh_bozkurt_2016, place={Orlando, FL, USA}, title={Soft, flexible 3D printed fibers for capacitive tactile sensing}, url={http://ieeexplore.ieee.org/document/7808918/}, DOI={10.1109/icsens.2016.7808918}, abstractNote={This study presents our latest efforts towards developing a force sensor array by weaving 3D printed functionalized polymer fibers. Silicone was used as the base polymer and carbon fillers were used to impart electrical conductivity. Two “H”-shaped fiber cross-sections oriented orthogonally acted as a parallel plate capacitor and were used for detecting normal forces. In this article, we present the fabrication method of the unique “H”-shaped fiber cross-section along with the investigation of the relation between applied force and measured capacitance. We also report the sensor response to variation in temperature. The sensing crossover was found to have a stable mechanical and electrical response in the force range of 0–6 N and the performance of this soft sensor was not significantly affected by temperature.}, booktitle={2016 ieee sensors}, author={Kapoor, A. and McKnight, M. and Chatterjee, K. and Agcayazi, T. and Kausche, H. and ghosh and Bozkurt, A.}, year={2016}, pages={1–3} }
 @article{latif_whitmire_novak_bozkurt_2016, title={Sound Localization Sensors for Search and Rescue Biobots}, volume={16}, ISSN={["1558-1748"]}, DOI={10.1109/jsen.2015.2477443}, abstractNote={Recent advances in neural engineering have enabled direct control of insect locomotion through neural and muscular stimulation. The resulting insect biobots, with a natural ability to crawl through small spaces, offer unique advantages over traditional synthetic robots. A cyberphysical network of such biobots could prove useful for search and rescue applications in uncertain disaster environments. We present a vision-based automated system for an objective assessment of biobotic navigation capability on Madagascar hissing cockroaches. We report the most precise control results obtained with insect biobots so far both manually and autonomously. We also demonstrate autonomous control capability where a low-power insect-mounted array of microphones was used to localize a sound source and guide the biobot toward it. Forming a wireless mobile sensor network with directional and omnidirectional microphones distributed within the structure of a rubble pile could be useful for both environmental mapping and localization of trapped survivors under the rubble.}, number={10}, journal={IEEE SENSORS JOURNAL}, author={Latif, Tahmid and Whitmire, Eric and Novak, Tristan and Bozkurt, Alper}, year={2016}, month={May}, pages={3444–3453} }
 @inproceedings{dieffenderfer_wilkins_hood_beppler_daniele_bozkurt_2016, title={Towards a sweat-based wireless and wearable electrochemical sensor}, booktitle={2016 ieee sensors}, author={Dieffenderfer, J. and Wilkins, M. and Hood, C. and Beppler, E. and Daniele, M. A. and Bozkurt, A.}, year={2016} }
 @inproceedings{brugarolas_agcayazi_yuschak_roberts_sherman_bozkurt_2016, title={Towards a wearable system for continuous monitoring of sniffing and panting in dogs}, DOI={10.1109/bsn.2016.7516276}, abstractNote={Although numerous advances have been made in instrumental odor detection systems, these still cannot match the efficient sampling, odor discrimination, agile mobility and the olfactory acuity of odor detection dogs. A limiting step in using dogs to detect odors is the subjectivity of the translation of odor information processed by the dog to its handler. We present our preliminary efforts towards a wireless wearable system for continuous auscultation of respiratory behavior by recording internal sounds at the neck and chest by means of a commercially available electronic stethoscope to provide objective decision support for handlers. We have identified discrete features of sniffing and panting in the time domain and utilize event duration, event rate, event mean energy, and the number of consecutive events in a row to build a decision tree classifier. Since feature extraction requires segmentation of individual sniffing and panting events, we developed an adaptive method using short-time energy contour and an adaptive threshold. The performance of the system was evaluated on recordings from a Greyhound and a Labrador Retriever and achieved high classification accuracies.}, booktitle={International conference on wearable and implantable body sensor}, author={Brugarolas, R. and Agcayazi, T. and Yuschak, S. and Roberts, D. L. and Sherman, B. L. and Bozkurt, A.}, year={2016}, pages={292–295} }
 @inproceedings{latif_gong_dickey_sichitiu_bozkurt_2016, title={Using liquid metal alloy (EGaIn) to electrochemically enhance SS stimulation electrodes for biobotic applications}, DOI={10.1109/embc.2016.7591152}, abstractNote={Biobotics is an emerging and useful advent in the field of robotics which harnesses the mechanical power of live invertebrates and benefits from them as "working" animals. Most biobotic applications rely on neural or muscular stimulation through implanted electrodes for achieving direct control of their locomotory behavior. Degradation of stimulation efficiency is often noticed through extended usage, partly owing to incompatibility of implanted electrodes to the application. Our previous achievements in biobotics utilized commercially available stainless steel wires as stimulation electrodes due to its availability and lower cost. In this study, we look into the potential of using a liquid metal alloy, eutectic gallium-indium (EGaIn), as a means of enhancing properties of the stainless steel electrodes and its first time consideration as in vivo neurostimulation electrodes. We present in vitro analysis of the electrodes in terms of the electrolyte-electrode interface impedance and interface equivalent circuit model.}, booktitle={2016 38th annual international conference of the ieee engineering in medicine and biology society (embc)}, author={Latif, T. and Gong, F. Y. and Dickey, Michael and Sichitiu, Mihail L. and Bozkurt, A.}, year={2016}, pages={2141–2144} }
 @article{brugarolas_latif_dieffenderfer_walker_yuschak_sherman_roberts_bozkurt_2016, title={Wearable Heart Rate Sensor Systems for Wireless Canine Health Monitoring}, volume={16}, ISSN={["1558-1748"]}, DOI={10.1109/jsen.2015.2485210}, abstractNote={There is an increasing interest from dog handlers and veterinarians in an ability to continuously monitor dogs' vital signs (heart rate, heart rate variability, and respiratory rate) outside laboratory environments, with the aim of identifying physiological correlations to stress, distress, excitement, and other emotional states. We present a non-invasive wearable sensor system combining electrocardiogram (ECG), photoplethysmogram (PPG), and inertial measurement units (IMU) to remotely and continuously monitor the vital signs of dogs. To overcome the limitations imposed by the efficiently insulated skin and dense hair layers of dogs, we investigated the use of various styles of ECG electrodes and the enhancements of these by conductive polymer coatings. We also studied the incorporation of light guides and optical fibers for an efficient optical coupling of PPG sensors to the skin. Combined with our parallel efforts to use IMUs to identify dog behaviors, these physiological sensors will contribute to a canine-body area network to wirelessly and continuously collect data during canine activities with a long-term goal of effectively capturing and interpreting dogs' behavioral responses to environmental stimuli that may yield measurable benefits to handlers' interactions with their dogs.}, number={10}, journal={IEEE SENSORS JOURNAL}, author={Brugarolas, Rita and Latif, Tahmid and Dieffenderfer, James and Walker, Katherine and Yuschak, Sherrie and Sherman, Barbara L. and Roberts, David L. and Bozkurt, Alper}, year={2016}, month={May}, pages={3454–3464} }
 @article{misra_bozkurt_calhoun_jackson_jur_lach_lee_muth_oralkan_oeztuerk_et al._2015, title={Flexible Technologies for Self-Powered Wearable Health and Environmental Sensing}, volume={103}, ISSN={["1558-2256"]}, DOI={10.1109/jproc.2015.2412493}, abstractNote={This article provides the latest advances from the NSF Advanced Self-powered Systems of Integrated sensors and Technologies (ASSIST) center. The work in the center addresses the key challenges in wearable health and environmental systems by exploring technologies that enable ultra-long battery lifetime, user comfort and wearability, robust medically validated sensor data with value added from multimodal sensing, and access to open architecture data streams. The vison of the ASSIST center is to use nanotechnology to build miniature, self-powered, wearable, and wireless sensing devices that can enable monitoring of personal health and personal environmental exposure and enable correlation of multimodal sensors. These devices can empower patients and doctors to transition from managing illness to managing wellness and create a paradigm shift in improving healthcare outcomes. This article presents the latest advances in high-efficiency nanostructured energy harvesters and storage capacitors, new sensing modalities that consume less power, low power computation, and communication strategies, and novel flexible materials that provide form, function, and comfort. These technologies span a spatial scale ranging from underlying materials at the nanoscale to body worn structures, and the challenge is to integrate them into a unified device designed to revolutionize wearable health applications.}, number={4}, journal={PROCEEDINGS OF THE IEEE}, author={Misra, Veena and Bozkurt, Alper and Calhoun, Benton and Jackson, Thomas N. and Jur, Jesse S. and Lach, John and Lee, Bongmook and Muth, John and Oralkan, Oemer and Oeztuerk, Mehmet and et al.}, year={2015}, month={Apr}, pages={665–681} }
 @article{winters_brugarolas_majikes_mealin_yuschak_sherman_bozkurt_roberts_2015, title={Knowledge Engineering for Unsupervised Canine Posture Detection from IMU Data}, DOI={10.1145/2832932.2837015}, abstractNote={Training animals is a process that requires a significant investment of time and energy on the part of the trainer. One of the most basic training tasks is to train dogs to perform postures on cue. While it might be easy for a human trainer to see when an animal has performed the desired posture, it is much more difficult for a computer to determine this. Most work in this area uses accelerometer and/or gyroscopic data to produce data from an animal's current state, but this has limitations. Take for example a normal standing posture. From an accelerometer's perspective, it closely resembles the "laying down" posture, but the posture can look very different if the animal is standing still, versus walking, versus running, and might look completely different from a "standing on incline" posture. A human trainer can instantly tell the difference between these postures and behaviors, but the process is much more difficult for a computer. This paper demonstrates several algorithms for recognizing canine postures, as well as a system for building a computational model of a canine's potential postures, based solely on skeletal measurements. Existing techniques use labeled data, which can be difficult to acquire. We contribute a new technique for unsupervised posture detection, and compare the supervised technique to our new, unsupervised technique. Results indicate that the supervised technique performs with a mean 82.06% accuracy, while our unsupervised approach achieves a mean 74.25% accuracy, indicating that in some cases, our new unsupervised technique is capable of achieving comparable performance.}, journal={12TH ADVANCES IN COMPUTER ENTERTAINMENT TECHNOLOGY CONFERENCE (ACE15)}, author={Winters, Michael and Brugarolas, Rita and Majikes, John and Mealin, Sean and Yuschak, Sherrie and Sherman, Barbara L. and Bozkurt, Alper and Roberts, David}, year={2015} }
 @inbook{bozkurt_2015, title={Metamorphic neural interfaces with insects for remote controlled biobots}, ISBN={9781139629539}, url={http://dx.doi.org/10.1017/cbo9781139629539.016}, DOI={10.1017/cbo9781139629539.016}, abstractNote={Muscles are the mechanical actuators of the body controlled by neurons. We use these actuators to perform many actions during the activities of our daily life. Moreover, we have benefited throughout history from the muscle power of larger animals, for farming, transportation, and industry. However, the muscle power of insects has not yet been exploited reliably or reproducibly, although insects possess a much higher ratio of muscle force to body mass than most large domesticated mammals. The novel field of insect–machine interfaces (IMI) combines microtechnology and neuroengineering to benefit from the muscle power of insects in a “biobotic” manner. To facilitate this, Early Metamorphosis Insertion Technology (EMIT) provides a novel neurotechnological pathway for integrating microelectronic sensing and actuation platforms into insects during metamorphosis. Metamorphic development not only provides an elegant and effective method of mechanically affixing artificial systems in or on an insect, but also produces a reliable bioelectrical interface without any observable short-term adverse effect on insect flight behavior. As an application of biobotic control of insect locomotion, the first steps towards flight and gait navigation in moths and cockroaches are presented in this chapter.}, booktitle={Handbook of Bioelectronics}, publisher={Cambridge University Press}, author={Bozkurt, Alper}, editor={Carrara, Sandro and Iniewski, KrzysztofEditors}, year={2015}, month={Sep}, pages={183–194} }
 @inproceedings{misra_lach_bozkurt_calhoun_datta_oralkan_2015, title={Self-powered wearable sensor platforms for wellness}, booktitle={2015 International Conference on Compilers, Architecture and Synthesis for Embedded Systems (CASES)}, author={Misra, V. and Lach, J. and Bozkurt, A. and Calhoun, B. and Datta, S. and Oralkan, O.}, year={2015}, pages={187–187} }
 @article{mealin_winters_dominguez_marrero-garcia_bozkurt_sherman_roberts_2015, title={Towards the Non-Visual Monitoring of Canine Physiology in Real-Time by Blind Handlers}, DOI={10.1145/2832932.2837018}, abstractNote={One of the challenges to working with canines is that whereas humans are primarily vocal communicators, canines are primarily postural and behavioral communicators. It can take years to gain some level of proficiency at reading canine body language, even under the best of circumstances. In the case of guide dogs and visually-impaired handlers, this task is even more difficult. Luckily, new technology designed to help monitor canines may prove useful in helping handlers, especially those with visual impairments, to better understand and interpret what their working partners are feeling or saying. In prior work a light-weight, wearable, wireless physiological monitoring system was shown to be accurate for measuring canines' heart and respiratory rates [6]. In this paper, we consider the complementary problem of communicating physiological information to handlers. We introduce two non-visual interfaces for monitoring a canine's heart and respiratory rates, an audio interface and a vibrotactile interface. We also present the results of two initial studies to evaluate the efficacy of the interfaces. In the first study we found that many participants were more confident in detecting changes in heart and respiratory rate using the audio interface, however most of the time they were just as accurate with the vibrotactile interface with only a slight increase in detection latency.}, journal={12TH ADVANCES IN COMPUTER ENTERTAINMENT TECHNOLOGY CONFERENCE (ACE15)}, author={Mealin, Sean and Winters, Mike and Dominguez, Ignacio X. and Marrero-Garcia, Michelle and Bozkurt, Alper and Sherman, Barbara L. and Roberts, David L.}, year={2015} }
 @inproceedings{dieffenderfer_goodell_bent_beppler_jayakumar_yokus_jur_bozkurt_peden_2015, title={Wearable wireless sensors for chronic respiratory disease monitoring}, DOI={10.1109/bsn.2015.7299411}, abstractNote={We present a wearable sensor system consisting of a wristband and chest patch to enable the correlation of individual environmental exposure to health response for understanding impacts of ozone on chronic asthma conditions. The wrist worn device measures ambient ozone concentration, heart rate via plethysmography (PPG), three-axis acceleration, ambient temperature, and ambient relative humidity. The chest patch measures heart rate via electrocardiography (ECG) and PPG, respiratory rate via PPG, wheezing via a microphone, and three-axis acceleration. The data from each sensor is continually streamed to a peripheral data aggregation device, and is subsequently transferred to a dedicated server for cloud storage. The current generation of the system uses only commercially-off-the-shelf (COTS) components where the entire electronic structure of the wristband has dimensions of 3.1×4.1×1.2 cm3 while the chest patch electronics has a dimensions of 3.3×4.4×1.2 cm3. The power consumptions of the wristband and chest patch are 78 mW and 33 mW respectively where using a 400 mAh lithium polymer battery would operate the wristband for around 15 hours and the chest patch for around 36 hours.}, booktitle={2015 IEEE 12th International Conference on Wearable and Implantable Body Sensor Networks (BSN)}, author={Dieffenderfer, J. P. and Goodell, H. and Bent, B. and Beppler, E. and Jayakumar, R. and Yokus, M. and Jur, J. S. and Bozkurt, A. and Peden, D.}, year={2015} }
 @article{bozkurt_lobaton_sichitiu_hedrick_latif_dirafzoon_whitmire_verderber_marin_xiong_et al._2014, title={Biobotic Insect Swarm based Sensor Networks for Search and Rescue}, volume={9091}, ISSN={["1996-756X"]}, url={http://dx.doi.org/10.1117/12.2053906}, DOI={10.1117/12.2053906}, abstractNote={The potential benefits of distributed robotics systems in applications requiring situational awareness, such as search-and-rescue in emergency situations, are indisputable. The efficiency of such systems requires robotic agents capable of coping with uncertain and dynamic environmental conditions. For example, after an earthquake, a tremendous effort is spent for days to reach to surviving victims where robotic swarms or other distributed robotic systems might play a great role in achieving this faster. However, current technology falls short of offering centimeter scale mobile agents that can function effectively under such conditions. Insects, the inspiration of many robotic swarms, exhibit an unmatched ability to navigate through such environments while successfully maintaining control and stability. We have benefitted from recent developments in neural engineering and neuromuscular stimulation research to fuse the locomotory advantages of insects with the latest developments in wireless networking technologies to enable biobotic insect agents to function as search-and-rescue agents. Our research efforts towards this goal include development of biobot electronic backpack technologies, establishment of biobot tracking testbeds to evaluate locomotion control efficiency, investigation of biobotic control strategies with Gromphadorhina portentosa cockroaches and Manduca sexta moths, establishment of a localization and communication infrastructure, modeling and controlling collective motion by learning deterministic and stochastic motion models, topological motion modeling based on these models, and the development of a swarm robotic platform to be used as a testbed for our algorithms.}, journal={SIGNAL PROCESSING, SENSOR/INFORMATION FUSION, AND TARGET RECOGNITION XXIII}, publisher={SPIE}, author={Bozkurt, A. and Lobaton, E. and Sichitiu, Mihail L. and Hedrick, T. and Latif, T. and Dirafzoon, A. and Whitmire, E. and Verderber, A. and Marin, J. and Xiong, H. and et al.}, editor={Kadar, IvanEditor}, year={2014} }
 @inbook{bozkurt_mcconnell_2014, title={Bionanotechnological Advances in Neural Recording and Stimulation}, ISBN={9781315216188}, url={http://dx.doi.org/10.1201/b15283-19}, DOI={10.1201/b15283-19}, booktitle={Novel Advances in Microsystems Technologies and Their Applications}, publisher={CRC Press}, author={Bozkurt, Alper and McConnell, George C.}, editor={Francis, Laurent A.Editor}, year={2014}, pages={437–460} }
 @article{verderber_mcknight_bozkurt_2014, title={Early Metamorphic Insertion Technology for Insect Flight Behavior Monitoring}, ISSN={["1940-087X"]}, DOI={10.3791/50901}, abstractNote={Early Metamorphosis Insertion Technology (EMIT) is a novel methodology for integrating microfabricated neuromuscular recording and actuation platforms on insects during their metamorphic development. Here, the implants are fused within the structure and function of the neuromuscular system as a result of metamorphic tissue remaking. The implants emerge with the insect where the development of tissue around the electronics during pupal development results in a bioelectrically and biomechanically enhanced tissue interface. This relatively more reliable and stable interface would be beneficial for many researchers exploring the neural basis of the insect locomotion with alleviated traumatic effects caused during adult stage insertions. In this article, we implant our electrodes into the indirect flight muscles of Manduca sexta. Located in the dorsal-thorax, these main flight powering dorsoventral and dorsolongitudinal muscles actuate the wings and supply the mechanical power for up and down strokes. Relative contraction of these two muscle groups has been under investigation to explore how the yaw maneuver is neurophysiologically coordinated. To characterize the flight dynamics, insects are often tethered with wires and their flight is recorded with digital cameras. We also developed a novel way to tether Manduca sexta on a magnetically levitating frame where the insect is connected to a commercially available wireless neural amplifier. This set up can be used to limit the degree of freedom to yawing "only" while transmitting the related electromyography signals from dorsoventral and dorsolongitudinal muscle groups.}, number={89}, journal={JOVE-JOURNAL OF VISUALIZED EXPERIMENTS}, author={Verderber, Alexander and McKnight, Michael and Bozkurt, Alper}, year={2014}, month={Jul} }
 @inproceedings{dirafzoon_bethhauser_schornick_cole_bozkurt_lobaton_2014, title={Poster abstract: Cyborg-insect networks for mapping of unknown environments}, DOI={10.1109/iccps.2014.6843729}, abstractNote={Cyborg-insect networks are systems that take advantage of existing biological platforms such as cockroaches [2] by attaching small instrumented payloads for sensing and motion control. These agents can be used in applications such as mapping and exploration of environment for emergency response (e.g., search and rescue operations after earthquakes, tsunamis, hurricanes, etc.) These agents can gain access to locations that may not be reachable otherwise by moving underground through smaller locations. The power limitations of such platforms place restrictions on sensing, communication, and motion control. Hence, traditional mapping and exploration techniques may not perform well under these adverse conditions. We propose a robust approach to obtain a topological map of an unknown environment using the coordinate free sensory data obtained from these cyborg-insect networks. In order to minimize control input, we take advantage of the natural behavior of insects in order to estimate a topological model of the environment based only on neighbor-to-neighbor interactions.}, booktitle={2014 acm/ieee international conference on cyber-physical systems (iccps)}, author={Dirafzoon, A. and Bethhauser, J. and Schornick, J. and Cole, J. and Bozkurt, A. and Lobaton, Edgar}, year={2014}, pages={216–216} }
 @article{uzsák_dieffenderfer_bozkurt_schal_2014, title={Social facilitation of insect reproduction with motor-driven tactile stimuli}, volume={281}, ISSN={0962-8452 1471-2954}, url={http://dx.doi.org/10.1098/rspb.2014.0325}, DOI={10.1098/rspb.2014.0325}, abstractNote={Tactile stimuli provide animals with important information about the environment, including physical features such as obstacles, and biologically relevant cues related to food, mates, hosts and predators. The antennae, the principal sensory organs of insects, house an array of sensory receptors for olfaction, gustation, audition, nociception, balance, stability, graviception, static electric fields, and thermo-, hygro- and mechanoreception. The antennae, being the anteriormost sensory appendages, play a prominent role in social interactions with conspecifics that involve primarily chemosensory and tactile stimuli. In the German cockroach (Blattella germanica) antennal contact during social interactions modulates brain-regulated juvenile hormone production, ultimately accelerating the reproductive rate in females. The primary sensory modality mediating this social facilitation of reproduction is antennal mechanoreception. We investigated the key elements, or stimulus features, of antennal contact that socially facilitate reproduction in B. germanica females. Using motor-driven antenna mimics, we assessed the physiological responses of females to artificial tactile stimulation. Our results indicate that tactile stimulation with artificial materials, some deviating significantly from the native antennal morphology, can facilitate female reproduction. However, none of the artificial stimuli matched the effects of social interactions with a conspecific female.}, number={1783}, journal={Proceedings of the Royal Society B: Biological Sciences}, publisher={The Royal Society}, author={Uzsák, Adrienn and Dieffenderfer, James and Bozkurt, Alper and Schal, Coby}, year={2014}, month={May}, pages={20140325} }
 @inproceedings{dieffenderfer_beppler_novak_whitmire_jayakumar_randall_qu_rajagopalan_bozkurt_2014, title={Solar powered wrist worn acquisition system for continuous photoplethysmogram monitoring}, DOI={10.1109/embc.2014.6944289}, abstractNote={We present a solar-powered, wireless, wrist-worn platform for continuous monitoring of physiological and environmental parameters during the activities of daily life. In this study, we demonstrate the capability to produce photoplethysmogram (PPG) signals using this platform. To adhere to a low power budget for solar-powering, a 574nm green light source is used where the PPG from the radial artery would be obtained with minimal signal conditioning. The system incorporates two monocrystalline solar cells to charge the onboard 20mAh lithium polymer battery. Bluetooth Low Energy (BLE) is used to tether the device to a smartphone that makes the phone an access point to a dedicated server for long term continuous storage of data. Two power management schemes have been proposed depending on the availability of solar energy. In low light situations, if the battery is low, the device obtains a 5-second PPG waveform every minute to consume an average power of 0.57 mW. In scenarios where the battery is at a sustainable voltage, the device is set to enter its normal 30 Hz acquisition mode, consuming around 13.7 mW. We also present our efforts towards improving the charge storage capacity of our on-board super-capacitor.}, booktitle={2014 36th annual international conference of the ieee engineering in medicine and biology society (embc)}, author={Dieffenderfer, J. P. and Beppler, E. and Novak, T. and Whitmire, E. and Jayakumar, R. and Randall, C. and Qu, W. G. and Rajagopalan, R. and Bozkurt, A.}, year={2014}, pages={3142–3145} }
 @article{bozkurt_roberts_sherman_brugarolas_mealin_majikes_yang_loftin_2014, title={Toward Cyber-Enhanced Working Dogs for Search and Rescue}, volume={29}, ISSN={["1941-1294"]}, DOI={10.1109/mis.2014.77}, abstractNote={The authors introduce the fundamental building blocks for a cyber-enabled, computer-mediated communication platform to connect human and canine intelligence to achieve a new generation of Cyber-Enhanced Working Dog (CEWD). The use of monitoring technologies provides handlers with real-time information about the behavior and emotional state of their CEWDs and the environments they're working in for a more intelligent canine-human collaboration. From handler to dog, haptic feedback and auditory cues are integrated to provide remote command and feedback delivery. From dog to handler, multiple inertial measurement units strategically located on a harness are used to accurately detect posture and behavior, and concurrent noninvasive photoplethysmogram and electrocardiogram for physiological monitoring. The authors also discuss how CEWDs would be incorporated with a variety of other robotic and autonomous technologies to create next-generation intelligent emergency response systems. Using cyber-physical systems to supplement and augment the two-way information exchange between human handlers and dogs would amplify the remarkable sensory capacities of search and rescue dogs and help them save more lives.}, number={6}, journal={IEEE INTELLIGENT SYSTEMS}, author={Bozkurt, Alper and Roberts, David L. and Sherman, Barbara L. and Brugarolas, Rita and Mealin, Sean and Majikes, John and Yang, Pu and Loftin, Robert}, year={2014}, pages={32–39} }
 @inproceedings{latif_whitmire_novak_bozkurt_2014, title={Towards fenceless boundaries for solar powered insect biobots}, DOI={10.1109/embc.2014.6943927}, abstractNote={Demonstration of remote navigation with instrumented insects, such as the Madagascar Hissing Cockroach, Gromphadorhina portentosa, has enabled the concept of biobotic agents for search and rescue missions and environmental monitoring applications. The biobots can form the nodes of a mobile sensor network to be established, for example, in unknown and dynamic environments after natural disasters to pinpoint surviving victims. We demonstrate here, for the first time, the concept of an invisible fence for insect biobots with an ultimate goal of keeping insect biobots within a certain distance of each other or a base station to ensure a reliable wireless network. For extended mission durations, this fenceless boundary would also be used to guide insects towards light sources for autonomous solar charging of their on-board batteries.}, booktitle={2014 36th annual international conference of the ieee engineering in medicine and biology society (embc)}, author={Latif, T. and Whitmire, E. and Novak, T. and Bozkurt, A.}, year={2014}, pages={1670–1673} }
 @inproceedings{brugarolas_loftin_yang_roberts_sherman_bozkurt_2013, title={Behavior recognition based on machine learning algorithms for a wireless canine machine interface}, DOI={10.1109/bsn.2013.6575505}, abstractNote={Training and handling working dogs is a costly process and requires specialized skills and techniques. Less subjective and lower-cost training techniques would not only improve our partnership with these dogs but also enable us to benefit from their skills more efficiently. To facilitate this, we are developing a canine body-area-network (cBAN) to combine sensing technologies and computational modeling to provide handlers with a more accurate interpretation for dog training. As the first step of this, we used inertial measurement units (IMU) to remotely detect the behavioral activity of canines. Decision tree classifiers and Hidden Markov Models were used to detect static postures (sitting, standing, lying down, standing on two legs and eating off the ground) and dynamic activities (walking, climbing stairs and walking down a ramp) based on the heuristic features of the accelerometer and gyroscope data provided by the wireless sensing system deployed on a canine vest. Data was collected from 6 Labrador Retrievers and a Kai Ken. The analysis of IMU location and orientation helped to achieve high classification accuracies for static and dynamic activity recognition.}, booktitle={2013 IEEE International Conference on Body Sensor Networks (BSN)}, author={Brugarolas, R. and Loftin, R. T. and Yang, P. and Roberts, D. L. and Sherman, B. and Bozkurt, A.}, year={2013} }
 @inproceedings{verderber_mcknight_bozkurt_2013, title={Electromagnetic levitation platform for wireless study of insect flight neurophysiology}, DOI={10.1109/embc.2013.6609851}, abstractNote={An electromagnetic levitation platform for use in a light emitting diode (LED) arena based virtual reality environment was developed for wireless recording of neural and neuromuscular signals from the flight related muscle groups in Manduca sexta. The platform incorporates the use of Early Metamorphosis Insertion Technology to implant recording electrodes into the flight muscles of late stage pupal moths. Analysis of the insects' response to changes in the LED arena rotation direction indicate that this setup could be used to perform a variety of flight behavior studies during yaw maneuvers.}, booktitle={2013 35th annual international conference of the ieee engineering in medicine and biology society (embc)}, author={Verderber, A. and McKnight, M. and Bozkurt, A.}, year={2013}, pages={1720–1723} }
 @inproceedings{whitmire_latif_bozkurt_2013, title={Kinect-based system for automated control of terrestrial insect biobots}, DOI={10.1109/embc.2013.6609789}, abstractNote={Centimeter scale mobile biobots offer unique advantages in uncertain environments. Our previous experimentation has demonstrated neural stimulation techniques in order to control the motion of Madagascar hissing cockroaches. These trials relied on stimulation by a human operator using a remote control. We have developed a Kinect-based system for computer operated automatic control of cockroaches. Using image processing techniques and a radio transmitter, this platform both detects the position of the roach biobot and sends stimulation commands to an implanted microcontroller-based receiver. The work presented here enables repeatable experimentation and allows precise quantification of the line following capabilities of the roach biobot. This system will help refine our model for the stimulation response of the insect and improve our ability to direct them in increasingly dynamic situations.}, booktitle={2013 35th annual international conference of the ieee engineering in medicine and biology society (embc)}, author={Whitmire, E. and Latif, T. and Bozkurt, A.}, year={2013}, pages={1470–1473} }
 @inproceedings{brugarolas_roberts_sherman_bozkurt_2013, title={Machine learning based posture estimation for a wireless canine machine interface}, DOI={10.1109/biowireless.2013.6613658}, abstractNote={Effective training and accurate interpretation of canine behaviors are essential for dog welfare and to obtain the maximum benefits provided by working dogs. We are developing a canine body area network based interface to incorporate electronic sensing and computational behavior modeling into canine training, where computers will be able to provide real time feedback to trainers about canine behavior. In this study, we investigated the accuracy of machine learning algorithms in identifying canine posture through wireless inertial sensing with 3-axis accelerometers and 3-axis gyroscopes. Data was collected from two dogs performing a sequence of 5 postures (sit, stand, lie, stand on two legs, and eat off the ground). A two-stage cascade learning technique was used: one for differentiating samples of behaviors of interest from transitions between behaviors, and one for posture classification of the behaviors. The algorithms achieved high posture classification accuracies demonstrating potential to enable a real time canine computer interface.}, booktitle={Ieee topical conference on biomedical wireless technologies networks and}, author={Brugarolas, R. and Roberts, D. and Sherman, B. and Bozkurt, A.}, year={2013}, pages={10–12} }
 @article{tarsi_gould_chung_xu_bozkurt_butcher_2013, title={Method for non-optical quantification of in situ local soft tissue biomechanics}, volume={46}, ISSN={["0021-9290"]}, DOI={10.1016/j.jbiomech.2013.05.014}, abstractNote={Soft tissues exhibit significant biomechanical changes as they grow, adapt, and remodel under a variety of normal and pathogenic stimuli. Biomechanical measurement of intact soft tissues is challenging because of its large strain and nonlinear behavior. Tissue distention through applied vacuum pressure is an attractive method for acquiring local biomechanical information minimally invasive and non-destructive, but the current requirement for optical strain measurement limits its use. In this study, we implemented a novel flexible micro-electrode array placed within a cylindrical probe tip. We hypothesized that upon tissue distention, contact with each electrode would result in a precipitous voltage drop (from the resistive connection formed between input and output electrodes) across the array. Hence, tissue distention (strain) can be derived directly from the electrode array geometry. In pilot studies, we compared the electrode array measurements directly against optical deformation measurements in-situ of agar tissue phantoms and freshly isolated porcine tissue. Our results demonstrate that the probe derived stress–strain profiles and modulus measurements were statistically indistinguishable from optical measurement. We further show that electrode geometry can be scaled down to 50 μm in size (length and width) and spaced 50 μm apart without impairing measurement accuracy. These results establish a promising new method for minimally invasive local soft tissue biomechanical measurement, which may be useful for applications such as disease diagnosis and health monitoring.}, number={11}, journal={JOURNAL OF BIOMECHANICS}, author={Tarsi, Grant M. and Gould, Russell A. and Chung, Jaebum A. and Xu, Andrew Z. and Bozkurt, Alper and Butcher, Jonathan T.}, year={2013}, month={Jul}, pages={1938–1942} }
 @inproceedings{dieffenderfer_bair_bozkurt_2013, title={Towards a smart bandage with functional near infrared spectroscopy capability}, DOI={10.1109/biowireless.2013.6613659}, abstractNote={This paper presents our efforts towards a smart bandage with incorporated miniaturized wireless functional near infrared spectroscopy system as a sensor node for wearable body area networks. The built prototype was used to successfully transmit deoxygenation of forearm muscle tissue during pressure cuff induced ischemia through an established Bluetooth link. The system can run over 4 hours continuously sampling at 150 Hz with provided 90mAh lithium polymer batteries and transmit data to distances more than 75 meters.}, booktitle={Ieee topical conference on biomedical wireless technologies networks and}, author={Dieffenderfer, J. and Bair, M. C. and Bozkurt, A.}, year={2013}, pages={13–15} }
 @inproceedings{latif_bozkurt_2012, title={Line following terrestrial insect biobots}, DOI={10.1109/embc.2012.6346095}, abstractNote={The present day technology falls short in offering centimeter scale mobile robots that can function effectively under unknown and dynamic environmental conditions. Insects, on the other hand, exhibit an unmatched ability to navigate through a wide variety of environments and overcome perturbations by successfully maintaining control and stability. In this study, we use neural stimulation systems to wirelessly navigate cockroaches to follow lines to enable terrestrial insect biobots. We also propose a system-on-chip based ZigBee enabled wireless neurostimulation backpack system with on-board tissue-electrode bioelectrical coupling verification. Such a capability ensures an electrochemically safe stimulation and avoids irreversible damage to the interface which is often misinterpreted as habituation of the insect to the applied stimulation.}, booktitle={2012 annual international conference of the ieee engineering in medicine and biology society (embc)}, author={Latif, T. and Bozkurt, A.}, year={2012}, pages={972–975} }
 @inproceedings{brugarolas_roberts_sherman_bozkurt_2012, title={Posture estimation for a canine machine interface based training system}, DOI={10.1109/embc.2012.6346964}, abstractNote={Dogs and humans have worked in partnership throughout history thanks to dogs' unique capability of detecting signals in human voices or gestures and learning from human inputs. Traditional canine training methods rely solely on subjective visual observations made by trainers. We propose a canine body-area-network (cBAN) to incorporate context-aware sensing with objective detection algorithms to augment the sensitivity and specificity of human trainer's awareness of the dogs they are training. As an initial effort, we developed a Bluetooth-based wireless infrastructure and tested inertial measurement units as cBAN sensor nodes to electronically assess the posture of the dogs. As a result, we were able to optimize the sensor locations and distinguish different postures using the distinct patterns in the measured angles.}, booktitle={2012 annual international conference of the ieee engineering in medicine and biology society (embc)}, author={Brugarolas, R. and Roberts, D. and Sherman, B. and Bozkurt, A.}, year={2012}, pages={4489–4492} }
 @inproceedings{bozkurt_gilmour_lal_2011, title={Bioelectrical enhancement in tissue-electrode coupling with metamorphic-stage insertions for insect machine interfaces}, DOI={10.1109/iembs.2011.6091340}, abstractNote={Implanting microtechnologies into insects with an aim of domesticating its locomotion poses certain challenges, however, performing surgical implantation during the early stages of metamorphic growth was shown to mitigate some of the related detriments. This study reports the bioelectrical enhancement at the tissue-electrode interface allowed with these metamorphic stage insertions, where the electrodes implanted in the insect during the early pupal stages and right after emergence were compared. An average 1 kHz impedance of 8.9 kΩ was obtained with pupal stage inserted electrodes, ten days after the emergence, as compared to 12.1 kΩ observed when electrodes were implanted in the adult state. Charge storage capacity also increased to 52 mC/cm2 from 38 mC/cm2 with the early metamorphic insertions. The performed voltage excursion studies also confirmed the enhancement demonstrating an increase from 3.5 mC/cm2 to 5.1 mC/cm2 in the injectable amount of charge in the water window.}, booktitle={2011 Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC)}, author={Bozkurt, A. and Gilmour, R. and Lal, A.}, year={2011}, pages={5420–5423} }
 @article{bozkurt_gilmour_lal_2011, title={In Vivo Electrochemical Characterization of a Tissue-Electrode Interface During Metamorphic Growth}, volume={58}, ISSN={["1558-2531"]}, DOI={10.1109/tbme.2011.2158822}, abstractNote={The domestication of insect locomotion has been recently investigated through microelectrode-based systems implanted in the insect to tap into its neuromuscular system. Benefiting from developmental changes, the idea of performing such surgical implantation during metamorphic development enabled the fusion of engineered constructs to these living biological organisms. This study uses electrochemical analysis to provide a preliminary quantitative comparison of tissue-electrode coupling over the course of metamorphic development and after eclosion, where PEDOT:PSS coated gold electrodes are implanted in the insect during the early pupal stages and right after emergence. An average 1 kHz impedance of 8.9 kΩ was obtained with pupal stage inserted electrodes, with a stored charge of 52 mC/cm2 at the interface as characterized by cyclic voltammetry 10 days after emergence. 5.1 mC/cm2 of this charge was successfully injected into the tissue through charge balanced biphasic pulses. In comparison, implanted electrodes in the adult state caused a 1 kHz impedance of 12.1 kΩ, where the stored charge was 38 mC/cm2 with an injectable charge amount of 3.5 mC/cm2. Finally, to shed light on possible reasons for improvement in the bioelectrical coupling, equivalent circuit models were formed and the extracted parameters were correlated with metamorphic development of pupal tissue.}, number={8}, journal={IEEE TRANSACTIONS ON BIOMEDICAL ENGINEERING}, author={Bozkurt, Alper and Gilmour, Robert F., Jr. and Lal, Amit}, year={2011}, month={Aug} }
 @article{bozkurt_lal_2011, title={Low-cost flexible printed circuit technology based microelectrode array for extracellular stimulation of the invertebrate locomotory system}, volume={169}, ISSN={["0924-4247"]}, DOI={10.1016/j.sna.2011.05.015}, abstractNote={The biobotic control of invertebrates through functional electrical stimulation of neural and neuromuscular tissue is under active exploration. Implantable microelectrodes are often designed to be used in chronic long term applications in vertebrates and subjected to strict endurance and resolution requirements. However, these constraints can be relaxed in invertebrate-related applications to allow low cost production for high-volume markets. In this study, we propose flexible printed circuit board (flex-PCB) based electrodes for implantable neuromuscular stimulation, address related shortcomings, and suggest modifications in the fabrication process. We were able to obtain a charge storage capacity of 3.18 mC/cm2 and 1 kHz impedance of 52 kΩ with gold electroplated 100 μm × 100 μm electrode sites on the flex-PCB electrodes. The electrodeposition of iridium oxide and electrochemical polymerization of PEDOT with dopant PSS on microelectrodes enhanced the charge storage capacity to 38.9 and 124.3 mC/cm2 where the 1 kHz impedance magnitude was 16 kΩ and 3 kΩ, respectively. This improvement in electrochemical performance was also corroborated by current pulsed voltage excursion studies. The long term dip test in saline solution supports the potential of flex-PCB electrodes for neural electrostimulation of insects, while revealing potential instability in PEDOT-PSS coatings with continuous high current density pulsing.}, number={1}, journal={SENSORS AND ACTUATORS A-PHYSICAL}, author={Bozkurt, Alper and Lal, Amit}, year={2011}, month={Sep}, pages={89–97} }
 @article{bozkurt_gilmour_sinha_stern_lal_2009, title={Insect–Machine Interface Based Neurocybernetics}, volume={56}, ISSN={0018-9294 1558-2531}, url={http://dx.doi.org/10.1109/tbme.2009.2015460}, DOI={10.1109/tbme.2009.2015460}, abstractNote={We present details of a novel bioelectric interface formed by placing microfabricated probes into insect during metamorphic growth cycles. The inserted microprobes emerge with the insect where the development of tissue around the electronics during the pupal development allows mechanically stable and electrically reliable structures coupled to the insect. Remarkably, the insects do not react adversely or otherwise to the inserted electronics in the pupae stage, as is true when the electrodes are inserted in adult stages. We report on the electrical and mechanical characteristics of this novel bioelectronic interface, which we believe would be adopted by many investigators trying to investigate biological behavior in insects with negligible or minimal traumatic effect encountered when probes are inserted in adult stages. This novel insect-machine interface also allows for hybrid insect-machine platforms for further studies. As an application, we demonstrate our first results toward navigation of flight in moths. When instrumented with equipment to gather information for environmental sensing, such insects potentially can assist man to monitor the ecosystems that we share with them for sustainability. The simplicity of the optimized surgical procedure we invented allows for batch insertions to the insect for automatic and mass production of such hybrid insect-machine platforms. Therefore, our bioelectronic interface and hybrid insect-machine platform enables multidisciplinary scientific and engineering studies not only to investigate the details of insect behavioral physiology but also to control it.}, number={6}, journal={IEEE Transactions on Biomedical Engineering}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Bozkurt, A. and Gilmour, R.F. and Sinha, A. and Stern, D. and Lal, A.}, year={2009}, month={Jun}, pages={1727–1733} }
 @article{broadbelt_stahl_chen_mizrahi_lal_bozkurt_poppas_felsen_2007, title={Early upregulation of iNOS mRNA expression and increase in NO metabolites in pressurized renal epithelial cells}, volume={293}, ISSN={1931-857X 1522-1466}, url={http://dx.doi.org/10.1152/ajprenal.00238.2007}, DOI={10.1152/ajprenal.00238.2007}, abstractNote={Pressure is an important physiological regulator, but under abnormal conditions it may be a critical factor in the onset and progression of disease in many organs. In vivo, proximal tubular epithelial cells are subjected to pressure as a result of ureteral obstruction, which may influence the production of nitric oxide (NO), a ubiquitous multifunctional cytokine. To directly explore the effect of pressure on the expression and activity of NO synthase (NOS) in cultured proximal tubular epithelial cells, a novel pressure apparatus was developed. Cells were subjected to pressures of 20-120 mmHg over time (5 min-72 h). RT-PCR demonstrated an increase in inducible NOS (iNOS) and sGC, while endothelial NOS remained unchanged. Real-time PCR (qPCR) confirmed an earlier induction of iNOS transcript subjected to 60 mmHg compared with cytokine mix. iNOS protein expression was significantly increased following 60 mmHg of pressure for 24 h. Use of nuclear factor-kappaB inhibitors was shown to prevent the increase in iNOS expression following 60 mmHg for 2 h. NO and cGMP were increased with the application of pressure. The addition of the irreversible iNOS inhibitor (1400W) was shown to prevent this increase. We demonstrate that with the use of a simply designed apparatus, pressure led to an extremely early induction of iNOS and a rapid activation of NOS activity to increase NO and cGMP in proximal tubule epithelial cells. The rapid effects of pressure on iNOS may have important implications in the obstructed kidney.}, number={6}, journal={American Journal of Physiology-Renal Physiology}, publisher={American Physiological Society}, author={Broadbelt, Nalini V. and Stahl, Peter J. and Chen, Jie and Mizrahi, Moshe and Lal, Amit and Bozkurt, Alper and Poppas, Dix P. and Felsen, Diane}, year={2007}, month={Dec}, pages={F1877–F1888} }
 @article{bozkurt_rosen_rosen_onaral_2005, title={A portable near infrared spectroscopy system for bedside monitoring of newborn brain}, volume={4}, ISSN={1475-925X}, url={http://dx.doi.org/10.1186/1475-925x-4-29}, DOI={10.1186/1475-925x-4-29}, abstractNote={Newborns with critical health conditions are monitored in neonatal intensive care units (NICU). In NICU, one of the most important problems that they face is the risk of brain injury. There is a need for continuous monitoring of newborn's brain function to prevent any potential brain injury. This type of monitoring should not interfere with intensive care of the newborn. Therefore, it should be non-invasive and portable.In this paper, a low-cost, battery operated, dual wavelength, continuous wave near infrared spectroscopy system for continuous bedside hemodynamic monitoring of neonatal brain is presented. The system has been designed to optimize SNR by optimizing the wavelength-multiplexing parameters with special emphasis on safety issues concerning burn injuries. SNR improvement by utilizing the entire dynamic range has been satisfied with modifications in analog circuitry.As a result, a shot-limited SNR of 67 dB has been achieved for 10 Hz temporal resolution. The system can operate more than 30 hours without recharging when an off-the-shelf 1850 mAh-7.2 V battery is used. Laboratory tests with optical phantoms and preliminary data recorded in NICU demonstrate the potential of the system as a reliable clinical tool to be employed in the bedside regional monitoring of newborn brain metabolism under intensive care.}, number={29}, journal={BioMedical Engineering OnLine}, publisher={Springer Nature}, author={Bozkurt, Alper and Rosen, Arye and Rosen, Harel and Onaral, Banu}, year={2005} }
 @article{bozkurt_onaral_2004, title={Safety assessment of near infrared light emitting diodes for diffuse optical measurements}, volume={3}, ISSN={1475-925X}, url={http://dx.doi.org/10.1186/1475-925x-3-9}, DOI={10.1186/1475-925x-3-9}, abstractNote={Near infrared (NIR) light has been used widely to monitor important hemodynamic parameters in tissue non-invasively. Pulse oximetry, near infrared spectroscopy, and diffuse optical tomography are examples of such NIR light-based applications. These and other similar applications employ either lasers or light emitting diodes (LED) as the source of the NIR light. Although the hazards of laser sources have been addressed in regulations, the risk of LED sources in such applications is still unknown.Temperature increase of the human skin caused by near infrared LED has been measured by means of in-vivo and in-vitro experiments. Effects of the conducted and radiated heat in the temperature increase have been analyzed separately.Elevations in skin temperature up to 10 degrees C have been observed. The effect of radiated heat due to NIR absorption is low--less than 0.5 degrees C--since emitted light power is comparable to the NIR part of sunlight. The conducted heat due to semiconductor junction of the LED can cause temperature increases up to 9 degrees C. It has been shown that adjusting operational parameters by amplitude modulating or time multiplexing the LED decreases the temperature increase of the skin significantly.In this study, we demonstrate that the major risk source of the LED in direct contact with skin is the conducted heat of the LED semiconductor junction, which may cause serious skin burns. Adjusting operational parameters by amplitude modulating or time multiplexing the LED can keep the LED within safe temperature ranges.}, number={9}, journal={BioMedical Engineering OnLine}, publisher={Springer Nature}, author={Bozkurt, Alper and Onaral, Banu}, year={2004}, month={Mar} }