@article{hossain_li_sennik_jur_bradford_2022, title={Adhesive free, conformable and washable carbon nanotube fabric electrodes for biosensing}, volume={6}, ISSN={["2397-4621"]}, DOI={10.1038/s41528-022-00230-3}, abstractNote={Abstract Skin-mounted wearable electronics are attractive for continuous health monitoring and human-machine interfacing. The commonly used pre-gelled rigid and bulky electrodes cause discomfort and are unsuitable for continuous long-term monitoring applications. Here, we design carbon nanotubes (CNTs)-based electrodes that can be fabricated using different textile manufacturing processes. We propose woven and braided electrode design using CNTs wrapped textile yarns which are highly conformable to skin and measure a high-fidelity electrocardiography (ECG) signal. The skin-electrode impedance analysis revealed size-dependent behavior. To demonstrate outstanding wearability, we designed a seamless knit electrode that can be worn as a bracelet. The designed CNT-based dry electrodes demonstrated record high signal-to-noise ratios and were very stable against motion artifacts. The durability test of the electrodes exhibited robustness to laundering and practicality for reusable and sustainable applications.}, number={1}, journal={NPJ FLEXIBLE ELECTRONICS}, author={Hossain, Md. Milon and Li, Braden M. M. and Sennik, Busra and Jur, Jesse S. S. and Bradford, Philip D. D.}, year={2022}, month={Dec} }
 @article{rosenberg_weiner_shahariar_li_peavey_mills_losego_jur_2022, title={Design of a scalable, flexible, and durable thermoelectric cooling device for soft electronics using Kirigami cut patterns}, volume={7}, ISSN={["2058-8585"]}, DOI={10.1088/2058-8585/ac48a0}, abstractNote={Abstract A flexible, soft thermoelectric cooling device is presented that shows potential for human cooling applications in wearable technologies and close-to-body applications. Current developments lack integration feasibility due to non-scalable assembly procedures and unsuitable materials for comfortable and durable integration into products. Our devices have been created and tested around the need to conform to the human body which we have quantified through the creation of a repeatable drape testing procedure, a metric used in the textile industry. Inspired by mass manufacturing constraints, our flexible thermoelectric devices are created using commercially available materials and scalable processing techniques. Thermoelectric legs are embedded in a foam substrate to provide flexibility, while Kirigami-inspired cuts are patterned on the foam to provide the drape necessary for mimicking the performance of textile and close to body materials. In total, nine different configurations, three different fill factors and three different Kirigami cut patterns were fabricated and inspected for thermal characterization, mechanical testing, flexibility and drape. Our studies show that adding Kirigami patterns can increase the durability of the device, improve the flexibility, decrease the drape coefficient, and have <1% of impact on cooling performance at higher fill factors (>1.5%), reaching temperature differences up to 4.39 °C ± 0.17 °C between the hot and cold faces of the device. These thermoelectric cooling devices show great flexibility, durability, and cooling for integration into soft cooling products.}, number={1}, journal={FLEXIBLE AND PRINTED ELECTRONICS}, author={Rosenberg, Z. B. and Weiner, N. C. and Shahariar, H. and Li, B. M. and Peavey, J. L. and Mills, A. C. and Losego, M. D. and Jur, J. S.}, year={2022}, month={Mar} }
 @article{li_reese_ingram_huddleston_jenkins_zaets_reuter_grogg_nelson_zhou_et al._2022, title={Textile-Integrated Liquid Metal Electrodes for Electrophysiological Monitoring}, volume={7}, ISSN={["2192-2659"]}, url={https://doi.org/10.1002/adhm.202200745}, DOI={10.1002/adhm.202200745}, abstractNote={Abstract Next generation textile‐based wearable sensing systems will require flexibility and strength to maintain capabilities over a wide range of deformations. However, current material sets used for textile‐based skin contacting electrodes lack these key properties, which hinder applications such as electrophysiological sensing. In this work, a facile spray coating approach to integrate liquid metal nanoparticle systems into textile form factors for conformal, flexible, and robust electrodes is presented. The liquid metal system employs functionalized liquid metal nanoparticles that provide a simple “peel‐off to activate” means of imparting conductivity. The spray coating approach combined with the functionalized liquid metal system enables the creation of long‐term reusable textile‐integrated liquid metal electrodes (TILEs). Although the TILEs are dry electrodes by nature, they show equal skin‐electrode impedances and sensing capabilities with improved wearability compared to commercial wet electrodes. Biocompatibility of TILEs in an in vivo skin environment is demonstrated, while providing improved sensing performance compared to previously reported textile‐based dry electrodes. The “spray on dry—behave like wet” characteristics of TILEs opens opportunities for textile‐based wearable health monitoring, haptics, and augmented/virtual reality applications that require the use of flexible and conformable dry electrodes.}, journal={ADVANCED HEALTHCARE MATERIALS}, author={Li, Braden M. and Reese, Brandon L. and Ingram, Katherine and Huddleston, Mary E. and Jenkins, Meghan and Zaets, Allison and Reuter, Matthew and Grogg, Matthew W. and Nelson, M. Tyler and Zhou, Ying and et al.}, year={2022}, month={Jul} }
 @article{li_ju_zhou_knowles_rosenberg_flewwellin_kose_jur_2021, title={Airbrushed PVDF-TrFE Fibrous Sensors for E-Textiles}, volume={3}, ISSN={["2637-6113"]}, url={https://doi.org/10.1021/acsaelm.1c00802}, DOI={10.1021/acsaelm.1c00802}, abstractNote={The low-temperature processing, inherent flexibility, and biocompatibility of piezoelectric polymers such as poly(vinylidene fluoride) (PVDF)-based materials enable the creation of soft wearable sensors, energy harvesters, and actuators. Of the various processing techniques, electrospinning is the most widely adopted process to form PVDF nanofiber scaffolds with enhanced piezoelectric properties such that they do not require further post-processing such as mechanical drawing, electrical poling, or thermal annealing. However, electrospinning requires long periods of time to form sufficiently thick PVDF nanofiber scaffolds and requires extremely high voltages to form scaffolds with enhanced piezoelectric properties, which limits the number of usable substrates, thus restricting the integration and use of electrospun PVDF scaffolds into wearable textile platforms. In this work, we propose a facile processing technique to airbrush PVDF–trifluoroethylene (TrFE) nanofiber scaffolds directly onto textile substrates. We tune the polymer concentration (4, 6, and 8 wt %) and the spray distance (5, 12.5, and 20 cm) to understand their effects on the morphology and crystal structure of the fibrous scaffolds. The characterization results show that increasing the polymer wt % encourages the formation of fibrous morphologies and a β-phase crystal structure. We then demonstrate how the airbrushed PVDF–TrFE scaffolds can be easily integrated onto conductive inkjet-printed nonwoven textile substrates to form airbrushed piezoelectric textile devices (APTDs). The APTDs exhibit maximum open-circuit voltages of 667.1 ± 162.1 mV under tapping and 276.9 ± 59.0 mV under bending deformations. The APTDs also show an areal power density of 0.04 μW/cm2, which is 40× times higher compared to previously reported airbrushed PVDF scaffolds. Lastly, we sew APTDs into wearable textile platforms to create fully textile-integrated devices with applications in sensing a basketball shooting form.}, number={12}, journal={ACS APPLIED ELECTRONIC MATERIALS}, publisher={American Chemical Society (ACS)}, author={Li, Braden M. and Ju, Beomjun and Zhou, Ying and Knowles, Caitlin G. and Rosenberg, Zoe and Flewwellin, Tashana J. and Kose, Furkan and Jur, Jesse S.}, year={2021}, month={Dec}, pages={5307–5326} }
 @article{li_mills_flewwellin_herzberg_bosari_lim_jia_jur_2021, title={Influence of Armband Form Factors on Wearable ECG Monitoring Performance}, volume={21}, ISSN={["1558-1748"]}, DOI={10.1109/JSEN.2021.3059997}, abstractNote={In the current state of innovation in wearable technology, there is a vast array of biomonitoring devices available to record electrocardiogram (ECG) in users, a key indicator of cardiovascular health. Of these devices, armband form factors serve as a convenient all-in-one platform for integration of electronic systems; yet, much of the current literature does not address the appropriate electrode location nor contact pressures necessary to achieve reliable system level ECG sensing. Therefore, this paper will elucidate the role of electrode location and contact pressure on the ECG sensing performance of an electronic textile (E-textile) armband worn on the upper left arm. We first carry out an ECG signal characterization to validate the ideal armband electrode placement necessary to measure high quality signals without sacrificing practical assembly of the armband. We then model and experimentally quantify the contact pressure between the armband onto the upper arm as a function of armband size, a critical parameter dictating skin-electrode impedance and ECG signal quality. Finally, we evaluate how the size of the armband form factor affects its ECG sensing performance. Our experimental results confirm that armbands exhibiting modeled contact pressures between 500 Pa to 1500 Pa can acquire ECG signals. However, armband sizes exhibiting experimental contact pressures of 1297 ± 102 Pa demonstrate the best performance with similar signal-to-noise ratios (SNR) compared to wet electrode benchmarks. The fundamental design parameters discussed in this work serve as a benchmark for the design of future E-textile and wearable form factors with efficient sensing performance.}, number={9}, journal={IEEE SENSORS JOURNAL}, author={Li, Braden M. and Mills, Amanda C. and Flewwellin, Tashana J. and Herzberg, Jacklyn L. and Bosari, Azin Saberi and Lim, Michael and Jia, Yaoyao and Jur, Jesse S.}, year={2021}, month={May}, pages={11046–11060} }
 @article{ju_kim_li_knowles_mills_grace_jur_2021, title={Inkjet Printed Textile Force Sensitive Resistors for Wearable and Healthcare Devices}, volume={7}, ISSN={["2192-2659"]}, url={https://doi.org/10.1002/adhm.202100893}, DOI={10.1002/adhm.202100893}, abstractNote={Pressure sensors for wearable healthcare devices, particularly force sensitive resistors (FSRs) are widely used to monitor physiological signals and human motions. However, current FSRs are not suitable for integration into wearable platforms. This work presents a novel technique for developing textile FSRs (TFSRs) using a combination of inkjet printing of metal-organic decomposition silver inks and heat pressing for facile integration into textiles. The insulating void by a thermoplastic polyurethane (TPU) membrane between the top and bottom textile electrodes creates an architectured piezoresistive structure. The structure functions as a simple logic switch where under a threshold pressure the electrodes make contact to create conductive paths (on-state) and without pressure return to the prior insulated condition (off-state). The TFSR can be controlled by arranging the number of layers and hole diameters of the TPU spacer to specify a wide range of activation pressures from 4.9 kPa to 7.1 MPa. For a use-case scenario in wearable healthcare technologies, the TFSR connected with a readout circuit and a mobile app shows highly stable signal acquisition from finger movement. According to the on/off state of the TFSR with LED bulbs by different weights, it can be utilized as a textile switch showing tactile feedback.}, journal={ADVANCED HEALTHCARE MATERIALS}, author={Ju, Beomjun and Kim, Inhwan and Li, Braden M. and Knowles, Caitlin G. and Mills, Amanda and Grace, Landon and Jur, Jesse S.}, year={2021}, month={Jul} }
 @article{kim_ju_zhou_li_jur_2021, title={Microstructures in All-Inkjet-Printed Textile Capacitors with Bilayer Interfaces of Polymer Dielectrics and Metal-Organic Decomposition Silver Electrodes}, volume={13}, ISSN={["1944-8252"]}, url={https://doi.org/10.1021/acsami.1c01827}, DOI={10.1021/acsami.1c01827}, abstractNote={Soft printed electronics exhibit unique structures and flexibilities suited for a plethora of wearable applications. However, forming scalable, reliable multilayered electronic devices with heterogeneous material interfaces on soft substrates, especially on porous and anisotropic structures, is highly challenging. In this study, we demonstrate an all-inkjet-printed textile capacitor using a multilayered structure of bilayer polymer dielectrics and particle-free metal–organic decomposition (MOD) silver electrodes. Understanding the inherent porous/anisotropic microstructure of textiles and their surface energy relationship was an important process step for successful planarization. The MOD silver ink formed a foundational conductive layer through the uniform encapsulation of individual fibers without blocking fiber interstices. Urethane-acrylate and poly(4-vinylphenol)-based bilayers were able to form a planarized dielectric layer on polyethylene terephthalate textiles. A unique chemical interaction at the interfaces of bilayer dielectrics performed a significant role in insulating porous textile substrates resulting in high chemical and mechanical durability. In this work, we demonstrate how textiles' unique microstructures and bilayer dielectric layer designs benefit reliability and scalability in the inkjet process as well as the use in wearable electronics with electromechanical performance.}, number={20}, journal={ACS APPLIED MATERIALS & INTERFACES}, publisher={American Chemical Society (ACS)}, author={Kim, Inhwan and Ju, Beomjun and Zhou, Ying and Li, Braden M. and Jur, Jesse S.}, year={2021}, month={May}, pages={24081–24094} }
 @article{ruiz_ridder_fan_gong_li_mills_cobarrubias_strohmaier_jur_lach_2021, title={Self-Powered Cardiac Monitoring: Maintaining Vigilance With Multi-Modal Harvesting and E-Textiles}, volume={21}, ISSN={["1558-1748"]}, DOI={10.1109/JSEN.2020.3017706}, abstractNote={Remote patient monitoring has emerged from the intersection of engineering and medicine. Advances in sensors, circuits and systems have made possible the implementation of small, wearable devices capable of collecting and streaming data for long periods of time to help physicians track diseases and detect conditions in a non-intrusive manner. Cardiac monitoring comprises many of these applications, with the need to capture transient cardiac events motivating the adoption of wearable monitors in standard clinical practice. However, user burden and battery life limit the duration of monitoring or require heavy duty cycling, thus preventing the adoption of these technologies for use cases that require long-term vigilant monitoring, in which the sensor system cannot miss a critical cardiac event. To overcome these challenges, this paper introduces a self-powered system for uninterrupted vigilant cardiac and activity monitoring that senses and streams electrocardiogram (ECG) and motion data continuously to a smartphone while consuming only 683~μW on average. To achieve self-powered operation under environmental and wearability constraints, the system incorporates an energy combining technique to support multi-modal energy harvesting from indoor solar and thermoelectric energy. A custom ECG shirt made of a knitted compression fabric with embedded dry electrodes addresses issues of user comfort, skin irritation and motion artifacts. Vigilant Atrial Fibrillation (AF) monitoring is used as an example case study, analyzing sampling frequency and bit-depth quantization and their correlation to vigilant, self-powered operation. The integrated system demonstrates an important step forward for remote patient monitoring beyond the clinic.}, number={2}, journal={IEEE SENSORS JOURNAL}, author={Ruiz, Luis Javier Lopez and Ridder, Matthew and Fan, Dawei and Gong, Jiaqi and Li, Braden Max and Mills, Amanda C. and Cobarrubias, Elizabeth and Strohmaier, Jason and Jur, Jesse S. and Lach, John}, year={2021}, month={Jan}, pages={2263–2276} }
 @article{li_yildiz_mills_flewwellin_bradford_jur_2020, title={Iron-on carbon nanotube (CNT) thin films for biosensing E-Textile applications}, volume={168}, ISSN={["1873-3891"]}, DOI={10.1016/j.carbon.2020.06.057}, abstractNote={Conductive carbon nanotube-thermoplastic polyurethane (CNT-TPU) composite thin films are patterned and integrated onto knitted textile substrates to form electronic textile (E-Textile) dry electrodes. Vertically aligned CNT arrays are mechanically drawn into thin CNT sheets and infiltrated with a TPU solution to form the CNT-TPU thin films. The CNT-TPU thin films are then heat laminated onto knitted textile substrates to form dry E-Textile electrodes. To understand the wearability of our CNT-TPU thin films we perform an in-depth analysis of the films’ electromechanical properties, electrical impedance, and electrocardiogram (ECG) sensing performance. The electromechanical coupling between the CNT thin films and knitted textile substrates show a strong anisotropic dependence between the CNT film alignment and textile knit structure. Further analysis into the CNT thin films reveal that larger electrode sizes with a larger number of CNT sheet layers in the film, lead to more favorable impedance behaviors and ECG sensing capabilities. As a wearable demonstration, we fabricate a textile arm sleeve integrated with CNT thin film electrodes to form an ECG sensing E-Textile system. The proposed E-Textile sleeve demonstrates the practicality of our CNT thin films and show promise for other E-Textile and wearable applications.}, journal={CARBON}, author={Li, Braden M. and Yildiz, Ozkan and Mills, Amanda C. and Flewwellin, Tashana J. and Bradford, Philip D. and Jur, Jesse S.}, year={2020}, month={Oct}, pages={673–683} }