@article{shin_kim_jang_han_lee_ko_yang_rajaram_han_kang_et al._2024, title={Highly Elastic, Bioresorbable Polymeric Materials for Stretchable, Transient Electronic Systems}, volume={16}, ISSN={["2150-5551"]}, DOI={10.1007/s40820-023-01268-2}, abstractNote={Abstract}, number={1}, journal={NANO-MICRO LETTERS}, author={Shin, Jeong-Woong and Kim, Dong-Je and Jang, Tae-Min and Han, Won Bae and Lee, Joong Hoon and Ko, Gwan-Jin and Yang, Seung Min and Rajaram, Kaveti and Han, Sungkeun and Kang, Heeseok and et al.}, year={2024}, month={Dec} }
 @article{shin_kim_jang_han_lee_ko_yang_rajaram_han_kang_et al._2024, title={Highly Elastic, Bioresorbable Polymeric Materials for Stretchable, Transient Electronic Systems (Vol 16, Pg 102, 2024)}, volume={16}, ISSN={["2150-5551"]}, DOI={10.1007/s40820-024-01376-7}, number={1}, journal={NANO-MICRO LETTERS}, author={Shin, Jeong-Woong and Kim, Dong-Je and Jang, Tae-Min and Han, Won Bae and Lee, Joong Hoon and Ko, Gwan-Jin and Yang, Seung Min and Rajaram, Kaveti and Han, Sungkeun and Kang, Heeseok and et al.}, year={2024}, month={Dec} }
 @article{garland_song_ma_kim_vazquez-guardado_hashkavayi_ganeshan_sharma_ryu_lee_et al._2023, title={A Miniaturized, Battery-Free, Wireless Wound Monitor That Predicts Wound Closure Rate Early}, volume={7}, ISSN={["2192-2659"]}, url={http://dx.doi.org/10.1002/adhm.202301280}, DOI={10.1002/adhm.202301280}, abstractNote={Abstract}, journal={ADVANCED HEALTHCARE MATERIALS}, publisher={Wiley}, author={Garland, Nate T. and Song, Joseph W. and Ma, Tengfei and Kim, Yong Jae and Vazquez-Guardado, Abraham and Hashkavayi, Ayemeh Bagheri and Ganeshan, Sankalp Koduvayur and Sharma, Nivesh and Ryu, Hanjun and Lee, Min-Kyu and et al.}, year={2023}, month={Jul} }
 @article{garland_kaveti_bandodkar_2023, title={Biofluid-Activated Biofuel Cells, Batteries, and Supercapacitors: A Comprehensive Review}, volume={11}, ISSN={["1521-4095"]}, url={http://dx.doi.org/10.1002/adma.202303197}, DOI={10.1002/adma.202303197}, abstractNote={Abstract}, journal={ADVANCED MATERIALS}, publisher={Wiley}, author={Garland, Nate T. and Kaveti, Rajaram and Bandodkar, Amay J.}, year={2023}, month={Nov} }
 @article{han_kim_kim_ko_shin_jang_han_kang_lim_eom_et al._2023, title={Electric Eel-Inspired Soft Electrocytes for Solid-State Power Systems}, volume={10}, ISSN={["1616-3028"]}, url={http://dx.doi.org/10.1002/adfm.202309781}, DOI={10.1002/adfm.202309781}, abstractNote={Abstract}, journal={ADVANCED FUNCTIONAL MATERIALS}, author={Han, Won Bae and Kim, Dong-Je and Kim, Yong Min and Ko, Gwan-Jin and Shin, Jeong-Woong and Jang, Tae-Min and Han, Sungkeun and Kang, Heeseok and Lim, Jun Hyeon and Eom, Chan-Hwi and et al.}, year={2023}, month={Oct} }
 @article{greco_bandodkar_menciassi_2023, title={Emerging technologies in wearable sensors}, volume={7}, ISSN={["2473-2877"]}, DOI={10.1063/5.0153940}, abstractNote={This Editorial highlights some current challenges and emerging solutions in wearable sensors, a maturing field where interdisciplinary crosstalk is of paramount importance. Currently, investigation efforts are aimed at expanding the application scenarios and at translating early developments from basic research to widespread adoption in personal health monitoring for diagnostic and therapeutic purposes. This translation requires addressing several old and new challenges that are summarized in this editorial. The special issue “Emerging technologies in wearable sensors” includes four selected contributions from leading researchers, exploring the topic from different perspectives. The aim is to provide the APL Bioengineering readers with a solid and timely overall vision of the field and with some recent examples of wearable sensors, exploring new research avenues.}, number={2}, journal={APL BIOENGINEERING}, author={Greco, Francesco and Bandodkar, Amay J. J. and Menciassi, Arianna}, year={2023}, month={Jun} }
 @article{han_ko_yang_kang_lee_shin_jang_han_kim_lim_et al._2023, title={Micropatterned Elastomeric Composites for Encapsulation of Transient Electronics}, volume={17}, ISSN={["1936-086X"]}, url={http://dx.doi.org/10.1021/acsnano.3c03063}, DOI={10.1021/acsnano.3c03063}, abstractNote={Although biodegradable, transient electronic devices must dissolve or decompose via environmental factors, an effective waterproofing or encapsulation system is essential for reliable, durable operation for a desired period of time. Existing protection approaches use multiple or alternate layers of electrically inactive organic/inorganic elements combined with polymers; however, their high mechanical stiffness is not suitable for soft, time-dynamic biological tissues/skins/organs. Here, we introduce a stretchable, bioresorbable encapsulant using nanoparticle-incorporated elastomeric composites with modifications of surface morphology. Nature-inspired micropatterns reduce the diffusion area for water molecules, and embedded nanoparticles impede water permeation, which synergistically enhances the water-barrier performance. Empirical and theoretical evaluations validate the encapsulation mechanisms under strains. Demonstration of a soft, degradable shield with an optical component under a biological solution highlights the potential applicability of the proposed encapsulation strategy.}, number={15}, journal={ACS NANO}, publisher={American Chemical Society (ACS)}, author={Han, Won Bae and Ko, Gwan-Jin and Yang, Seung Min and Kang, Heeseok and Lee, Joong Hoon and Shin, Jeong-Woong and Jang, Tae-Min and Han, Sungkeun and Kim, Dong-Je and Lim, Jun Hyeon and et al.}, year={2023}, month={Jul}, pages={14822–14830} }
 @article{kaveti_lee_youn_jang_han_yang_shin_ko_kim_han_et al._2023, title={Soft, Long-Lived, Bioresorbable Electronic Surgical Mesh with Wireless Pressure Monitor and On-Demand Drug Delivery}, volume={12}, ISSN={["1521-4095"]}, url={https://doi.org/10.1002/adma.202307391}, DOI={10.1002/adma.202307391}, abstractNote={Abstract}, journal={ADVANCED MATERIALS}, author={Kaveti, Rajaram and Lee, Joong Hoon and Youn, Joong Kee and Jang, Tae-Min and Han, Won Bae and Yang, Seung Min and Shin, Jeong-Woong and Ko, Gwan-Jin and Kim, Dong-Je and Han, Sungkeun and et al.}, year={2023}, month={Dec} }
 @article{kang_han_yang_ko_ryu_lee_shin_jang_rajaram_han_et al._2023, title={Stretchable and biodegradable triboelectric nanogenerator based on elastomeric nanocomposites}, volume={475}, ISSN={["1873-3212"]}, url={http://dx.doi.org/10.1016/j.cej.2023.146208}, DOI={10.1016/j.cej.2023.146208}, abstractNote={Biologically benign, dissolvable materials-based triboelectric nanogenerators hold significant potential as a sustainable power source for bioresorbable, transient electronic systems; however poor options in materials and engineering approaches are major obstacles to the desired electrical, physical, and mechanical properties, particularly when considering operations under restrictive, demanding conditions or environments. Here, we present an elastomeric composites-based triboelectric nanogenerator with a package of completely degradable materials. Assembly of inorganic nanoparticles with high charge affinity/permittivity and micro-pyramid structures with high surface area produces enhanced charge density and power outputs over those of existing elements. Study on mechanical and biochemical characteristics validates the capability of maintaining stable, long-life electrical outputs under cyclic tests and aqueous solutions. Demonstrations of energy harvesting at an artificial knee and self-powered motion sensing at a finger joint suggest the practical feasibility in versatile areas of biomedical and eco-resorbable electronics.}, journal={CHEMICAL ENGINEERING JOURNAL}, publisher={Elsevier BV}, author={Kang, Heeseok and Han, Won Bae and Yang, Seung Min and Ko, Gwan-Jin and Ryu, Yelynn and Lee, Joong Hoon and Shin, Jeong-Woong and Jang, Tae-Min and Rajaram, Kaveti and Han, Sungkeun and et al.}, year={2023}, month={Nov} }
 @article{mishra_garland_hewett_shamsi_dickey_bandodkar_2022, title={A Soft Wearable Microfluidic Patch with Finger-Actuated Pumps and Valves for On-Demand, Longitudinal, and Multianalyte Sweat Sensing}, volume={7}, ISSN={["2379-3694"]}, url={https://doi.org/10.1021/acssensors.2c01669}, DOI={10.1021/acssensors.2c01669}, abstractNote={Easy sample collection, physiological relevance, and ability to noninvasively and longitudinally monitor the human body are some of the key attributes of wearable sweat sensors. Examples typically include reversible sensors or an array of single-use sensors embedded in specialized microfluidics for temporal analysis of sweat. However, evolving this field to a level that truly represents "lab-on-skin" technology will require the incorporation of advanced functionalities that give the user the freedom to (1) choose the precise time for performing sample analysis and (2) select sensors from an array embedded within the device for performing condition-specific sample analysis. Here, we introduce new concepts in wearable microfluidic platforms that offer such capabilities. The described technology involves a series of finger-actuated pumps, valves, and sensors incorporated within soft, wearable microfluidics. The incoming sweat collects in the inlet chamber and can be analyzed by the user at the time of their choosing. On-demand sweat analyte assessment is achieved by pulling a thin tab to activate a pump which opens a valve and allows the pooled sweat to enter a chamber embedded with sensors for the desired analytes. The article describes a thorough characterization of the platform that demonstrates the robustness of the pumping, valving, and sensing aspects of the device under conditions mimicking real-life scenarios. A two-day-long human pilot study validates the system and illustrates the device's ability to offer on-demand, longitudinal, and multianalyte sensing. Our work represents the first example of a wearable system with such on-demand sensing capabilities and opens exciting avenues in sweat sensing for acquiring new insights into human physiology.}, number={10}, journal={ACS SENSORS}, author={Mishra, Navya and Garland, Nate T. and Hewett, Krystyn A. and Shamsi, Mohammad and Dickey, Michael D. and Bandodkar, Amay J.}, year={2022}, month={Oct}, pages={3169–3180} }
 @article{lee_ray_yoon_genovese_choi_lee_sahin_yan_ahn_bandodkar_et al._2022, title={A bioresorbable peripheral nerve stimulator for electronic pain block}, volume={8}, ISSN={["2375-2548"]}, DOI={10.1126/sciadv.abp9169}, abstractNote={Local electrical stimulation of peripheral nerves can block the propagation of action potentials, as an attractive alternative to pharmacological agents for the treatment of acute pain. Traditional hardware for such purposes, however, involves interfaces that can damage nerve tissue and, when used for temporary pain relief, that impose costs and risks due to requirements for surgical extraction after a period of need. Here, we introduce a bioresorbable nerve stimulator that enables electrical nerve block and associated pain mitigation without these drawbacks. This platform combines a collection of bioresorbable materials in architectures that support stable blocking with minimal adverse mechanical, electrical, or biochemical effects. Optimized designs ensure that the device disappears harmlessly in the body after a desired period of use. Studies in live animal models illustrate capabilities for complete nerve block and other key features of the technology. In certain clinically relevant scenarios, such approaches may reduce or eliminate the need for use of highly addictive drugs such as opioids.}, number={40}, journal={SCIENCE ADVANCES}, author={Lee, Geumbee and Ray, Emily and Yoon, Hong -Joon and Genovese, Sabrina and Choi, Yeon Sik and Lee, Min-Kyu and Sahin, Samet and Yan, Ying and Ahn, Hak-Young and Bandodkar, Amay J. and et al.}, year={2022}, month={Oct} }
 @article{huang_zhang_arafa_li_vazquez-guardado_ouyang_liu_madhvapathy_song_tzavelis_et al._2022, title={High performance dual-electrolyte magnesium-iodine batteries that can harmlessly resorb in the environment or in the body}, volume={9}, ISSN={["1754-5706"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85138827664&partnerID=MN8TOARS}, DOI={10.1039/d2ee01966c}, abstractNote={High-performance eco- and bio-resorbable magnesium–iodine batteries with >1.8 V output power cardiac pacemakers, wireless environmental monitors, thermal sensors, microcontrollers, and Bluetooth systems.}, number={10}, journal={ENERGY & ENVIRONMENTAL SCIENCE}, author={Huang, Ivy and Zhang, Yamin and Arafa, Hany M. and Li, Shupeng and Vazquez-Guardado, Abraham and Ouyang, Wei and Liu, Fei and Madhvapathy, Surabhi and Song, Joseph Woojin and Tzavelis, Andreas and et al.}, year={2022}, month={Sep} }
 @article{bandodkar_2022, title={Sweat sensors break free}, volume={10}, ISSN={["2520-1131"]}, DOI={10.1038/s41928-022-00856-1}, journal={NATURE ELECTRONICS}, author={Bandodkar, Amay J.}, year={2022}, month={Oct} }
 @article{stuart_jeang_slivicki_brown_burton_brings_alarcon-segovia_agyare_ruiz_tyree_et al._2022, title={Wireless, Battery-Free Implants for Electrochemical Catecholamine Sensing and Optogenetic Stimulation}, volume={12}, ISSN={["1936-086X"]}, DOI={10.1021/acsnano.2c09475}, abstractNote={Neurotransmitters and neuromodulators mediate communication between neurons and other cell types; knowledge of release dynamics is critical to understanding their physiological role in normal and pathological brain function. Investigation into transient neurotransmitter dynamics has largely been hindered due to electrical and material requirements for electrochemical stimulation and recording. Current systems require complex electronics for biasing and amplification and rely on materials that offer limited sensor selectivity and sensitivity. These restrictions result in bulky, tethered, or battery-powered systems impacting behavior and that require constant care of subjects. To overcome these challenges, we demonstrate a fully implantable, wireless, and battery-free platform that enables optogenetic stimulation and electrochemical recording of catecholamine dynamics in real time. The device is nearly 1/10th the size of previously reported examples and includes a probe that relies on a multilayer electrode architecture featuring a microscale light emitting diode (μ-LED) and a carbon nanotube (CNT)-based sensor with sensitivities among the highest recorded in the literature (1264.1 nA μM-1 cm-2). High sensitivity of the probe combined with a center tapped antenna design enables the realization of miniaturized, low power circuits suitable for subdermal implantation even in small animal models such as mice. A series of in vitro and in vivo experiments highlight the sensitivity and selectivity of the platform and demonstrate its capabilities in freely moving, untethered subjects. Specifically, a demonstration of changes in dopamine concentration after optogenetic stimulation of the nucleus accumbens and real-time readout of dopamine levels after opioid and naloxone exposure in freely behaving subjects highlight the experimental paradigms enabled by the platform.}, journal={ACS NANO}, author={Stuart, Tucker and Jeang, William J. and Slivicki, Richard A. and Brown, Bobbie J. and Burton, Alex and Brings, Victoria E. and Alarcon-Segovia, Lilian C. and Agyare, Prophecy and Ruiz, Savanna and Tyree, Amanda and et al.}, year={2022}, month={Dec} }
 @article{vázquez-guardado_yang_bandodkar_rogers_2021, title={Author Correction: Recent advances in neurotechnologies with broad potential for neuroscience research (Nature Neuroscience, (2020), 23, 12, (1522-1536), 10.1038/s41593-020-00739-8)}, volume={24}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85100771051&partnerID=MN8TOARS}, DOI={10.1038/s41593-021-00813-9}, abstractNote={A Correction to this paper has been published: https://doi.org/10.1038/s41593-021-00813-9.}, number={4}, journal={Nature Neuroscience}, author={Vázquez-Guardado, A. and Yang, Y. and Bandodkar, A.J. and Rogers, J.A.}, year={2021}, pages={611} }
 @article{alarcón-segovia_bandodkar_rogers_rintoul_2021, title={Catalytic effects of magnetic and conductive nanoparticles on immobilized glucose oxidase in skin sensors}, volume={32}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85109080111&partnerID=MN8TOARS}, DOI={10.1088/1361-6528/ac0668}, abstractNote={Wearable skin sensors is a promising technology for real-time health care monitoring. They are of particular interest for monitoring glucose in diabetic patients. The concentration of glucose in sweat can be more than two orders of magnitude lower than in blood. In consequence, the scientific and technological efforts are focused in developing new concepts to enhance the sensitivity, decrease the limit of detection (LOD) and reduce the response time (RT) of glucose skin sensors. This work explores the effect of adsorbed superparamagnetic magnetite nanoparticles (MNPs) and conductive nanoparticles (CNPs) on carbon nanotube substrates (CNTs) used to immobilize glucose oxidase enzyme in the working electrode of skin sensors. MNPs and CNPs are made of magnetite and gold, respectively. The performance of the sensors was tested in standard buffer solution, artificial sweat, fresh sweat and on the skin of a healthy volunteer during an exercise session. In the case of artificial sweat, the presence of MNPs accelerated the RT from 7 to 5 s at the expense of increasing the LOD from 0.017 to 0.022 mM with slight increase of the sensitivity from 4.90 to 5.09 μAm M−1 cm−2. The presence of CNPs greatly accelerated the RT from 7 to 2 s and lowered the LOD from 0.017 to 0.014 mM at the expense of a great diminution of the sensitivity from 4.90 to 4.09 μAm M−1 cm−2. These effects were explained mechanistically by analyzing the changes in the concentration of free oxygen and electrons promoted by MNPs and CNPs in the CNTs and its consequences on the the glucose oxidation process.}, number={37}, journal={Nanotechnology}, author={Alarcón-Segovia, L.C. and Bandodkar, A.J. and Rogers, J.A. and Rintoul, I.}, year={2021} }
 @book{rogers_choi_reeder_sekine_bandodkar_zhang_hexia_kim_ostojich_2021, title={Microfluidic systems for epidermal sampling and sensing}, number={10,925,523}, author={Rogers, John A. and Choi, Jungil and Reeder, Johnathan T. and Sekine, Yurina and Bandodkar, Amay J. and Zhang, Yi and Hexia, G.U.O. and Kim, Sungbong and Ostojich, Diana}, year={2021}, month={Feb} }
 @article{ray_ivanovic_curtis_franklin_guventurk_jeang_chafetz_gaertner_young_rebollo_et al._2021, title={Soft, skin-interfaced sweat stickers for cystic fibrosis diagnosis and management}, volume={13}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85103620338&partnerID=MN8TOARS}, DOI={10.1126/scitranslmed.abd8109}, abstractNote={A soft, wearable microfluidic platform collects and quantitatively analyzes sweat biomarkers to improve the diagnosis of cystic fibrosis.}, number={587}, journal={Science Translational Medicine}, author={Ray, T.R. and Ivanovic, M. and Curtis, P.M. and Franklin, D. and Guventurk, K. and Jeang, W.J. and Chafetz, J. and Gaertner, H. and Young, G. and Rebollo, S. and et al.}, year={2021} }
 @article{park_franz_ryu_luan_cotton_kim_chung_zhao_vazquez-guardado_yang_et al._2021, title={Three-dimensional, multifunctional neural interfaces for cortical spheroids and engineered assembloids}, volume={7}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85102661034&partnerID=MN8TOARS}, DOI={10.1126/sciadv.abf9153}, abstractNote={3D multifunctional frameworks, as flexible as a single strand of silk, modulate and measure neural activity of brain spheroids.}, number={12}, journal={Science Advances}, publisher={American Association for the Advancement of Science (AAAS)}, author={Park, Yoonseok and Franz, Colin K. and Ryu, Hanjun and Luan, Haiwen and Cotton, Kristen Y. and Kim, Jong Uk and Chung, Ted S. and Zhao, Shiwei and Vazquez-Guardado, Abraham and Yang, Da Som and et al.}, year={2021} }
 @article{bandodkar_ghaffari_rogers_2020, title={Don’t Sweat It: The Quest for Wearable Stress Sensors}, volume={2}, ISSN={2590-2385}, url={http://dx.doi.org/10.1016/j.matt.2020.03.004}, DOI={10.1016/j.matt.2020.03.004}, abstractNote={A nervous sweat may seem like an inconvenience, but your body could be releasing important signals. Herein, Gao and colleagues develop a wearable sensor with integrated microfluidics, immunoassays, and electronics for tracking cortisol in sweat—as a biomarker of stress. A nervous sweat may seem like an inconvenience, but your body could be releasing important signals. Herein, Gao and colleagues develop a wearable sensor with integrated microfluidics, immunoassays, and electronics for tracking cortisol in sweat—as a biomarker of stress. Stress is an intense, natural, and universal reaction that guides both cognitive and physical processes with beneficial short-term consequences attributed to “fight-or-flight” responses and harmful long-term consequences to health. Recent studies show that chronic stress accumulated over time can lead to debilitating outcomes such as cancer, coronary heart disease, accidental injuries, lung disease, liver disease and suicide.1Yao B.C. Meng L.B. Hao M.L. Zhang Y.M. Gong T. Guo Z.G. Chronic stress: a critical risk factor for atherosclerosis.J. Int. Med. Res. 2019; 47: 1429-1440Crossref Scopus (43) Google Scholar The World Health Organization estimates that stress-related disorders are one of the leading causes of disability globally and classifies stress as the “health epidemic of the 21st century”.2Kalia M. Assessing the economic impact of stress--the modern day hidden epidemic.Metabolism. 2002; 51: 49-53Abstract Full Text PDF PubMed Scopus (168) Google Scholar According to the American Psychological Association, over 80% of workers in the United States suffer from work-related stress, costing businesses a staggering $300 billion annually.3American Psychological Association42 Worrying Workplace Stress Statistics.https://www.stress.org/42-worrying-workplace-stress-statisticsDate: 2019Google Scholar Although the underlying causes can vary widely, the frequency and intensity of stressful events are rising sharply, due in part to the increasing influence of social media on daily life.4Aalbers G. McNally R.J. Heeren A. de Wit S. Fried E.I. Social media and depression symptoms: A network perspective.J. Exp. Psychol. Gen. 2019; 148: 1454-1462Crossref Scopus (117) Google Scholar Extensive research suggests that such stress can exacerbate or even cause serious medical conditions beyond those described above, including depressive and post-traumatic disorders, Alzheimer’s and Parkinson’s diseases, inflammatory conditions, and diabetes.5Deak T. Quinn M. Cidlowski J.A. Victoria N.C. Murphy A.Z. Sheridan J.F. Neuroimmune mechanisms of stress: sex differences, developmental plasticity, and implications for pharmacotherapy of stress-related disease.Stress. 2015; 18: 367-380Crossref PubMed Scopus (62) Google Scholar The clinical standard for assessing stress relies on questionnaires and surveys. The subjective nature of these techniques lack both quantitative rigor and temporal resolution necessary to aid in the development of precise medical interventions. Methodologies are, however, beginning to shift to techniques that exploit biochemical markers that are known to quantitatively relate to stress levels. A team of researchers at Caltech, led by Prof. Wei Gao, report an important contribution to this area of research in the form of a monitoring system that accurately captures instances of stress based on evaluation of key biomarker concentrations in sweat.6Torrente-Rodríguez R.M. Tu J. Yang Y. Min J. Wang M. Song Y. Yu Y. Xu C. Ye C. IsHak W.W. et al.Investigation of Cortisol Dynamics in Human Sweat Using a Graphene-Based Wireless mHealth System.Matter. 2020; 2 (this issue): 921-937Abstract Full Text Full Text PDF PubMed Scopus (161) Google Scholar The sensor platform leverages a collection of advances in nanotechnology, sweat sampling, immunosensing, and flexible, wireless electronics. At physiological levels, stress activates the sympathetic nervous system, the hypothalamic pituitary adrenal axis, and the immune system, collectively resulting in elevated levels of cortisol—a hormone that controls the body’s “fight-or-flight” reaction.7Kraemer W.J. French D.N. Spiering B.A. Volek J.S. Sharman M.J. Ratamess N.A. Judelson D.A. Silvestre R. Watson G. Gómez A. Maresh C.M. Cortitrol supplementation reduces serum cortisol responses to physical stress.Metabolism. 2005; 54: 657-668Abstract Full Text Full Text PDF PubMed Scopus (25) Google Scholar As a result, the concentration of cortisol yields a diagnostic correlate for stress.8Herane Vives A. De Angel V. Papadopoulos A. Strawbridge R. Wise T. Young A.H. Arnone D. Cleare A.J. The relationship between cortisol, stress and psychiatric illness: New insights using hair analysis.J. Psychiatr. Res. 2015; 70: 38-49Crossref PubMed Scopus (79) Google Scholar The conventional method for quantifying cortisol levels requires collection samples of blood using standard clinical techniques, and then analysis for cortisol using benchtop instrumentation. The result yields accurate measurements of cortisol levels but only at discrete time points, performed by trained personnel in specialized facilities. Practical limitations associated with these procedures prevent rapid medical interventions, thereby increasing the potential for stress related health complications. Emerging methods that rely on chemical analysis of hair and saliva provide non-invasive alternatives, but they retain requirements for manual collection and measurement. The wearable device reported by the Caltech team promises to enable continuous, real-time assessments of cortisol levels in a non-invasive, automated fashion through analysis of small volumes of sweat. The result could fundamentally change the way that we monitor stress levels on a daily basis. Sweat possesses several important attributes that are attractive for this type of non-invasive, autonomous physiological monitoring. For example, the human body produces a considerable amount of this relatively underexplored class of biofluid.9Taylor N.A.S. Machado-Moreira C.A. Regional variations in transepidermal water loss, eccrine sweat gland density, sweat secretion rates and electrolyte composition in resting and exercising humans.Extrem. Physiol. Med. 2013; 2: 4Crossref PubMed Scopus (279) Google Scholar More importantly, sweat contains a rich mixture of important biochemical markers,10Harvey C.J. LeBouf R.F. Stefaniak A.B. Formulation and stability of a novel artificial human sweat under conditions of storage and use.Toxicol. In Vitro. 2010; 24: 1790-1796Crossref PubMed Scopus (170) Google Scholar including cortisol,11Russell E. Koren G. Rieder M. Van Uum S.H. The detection of cortisol in human sweat: implications for measurement of cortisol in hair.Ther. Drug Monit. 2014; 36: 30-34PubMed Google Scholar that can yield insights into health status. Nevertheless, most prior studies of sweat focus mainly on handful of electrolytes, metabolites, and minerals. The work of Torrente-Rodríguez et al.6Torrente-Rodríguez R.M. Tu J. Yang Y. Min J. Wang M. Song Y. Yu Y. Xu C. Ye C. IsHak W.W. et al.Investigation of Cortisol Dynamics in Human Sweat Using a Graphene-Based Wireless mHealth System.Matter. 2020; 2 (this issue): 921-937Abstract Full Text Full Text PDF PubMed Scopus (161) Google Scholar represents a significant contribution to this growing field in the form of graphene-based, wireless, wearable devices capable of measuring cortisol levels in sweat, as it emerges from the surface of the skin (Figure 1). Systematic benchtop and human subject studies demonstrate the key features and capabilities of this system as well as strong correlations between cortisol levels in sweat, blood serum, and saliva samples. The results have direct implications for the continuous, accurate monitoring of stress levels, without the need for surveys or specialized equipment. The design and fabrication of these devices build on the authors’ expertise in graphene-based sweat sensors.12Yang Y. Song Y. Bo X. Min J. Pak O.S. Zhu L. Wang M. Tu J. Kogan A. Zhang H. et al.A laser-engraved wearable sensor for sensitive detection of uric acid and tyrosine in sweat.Nat. Biotechnol. 2020; 38: 217-224Crossref Scopus (432) Google Scholar The process begins with synthesis of graphene on a flexible film of polyimide via directed laser ablation. A layer of a conducting polymer–poly(pyrrole propionic acid) – grown on top of the graphene exposes surface chemical groups that promote attachment of an anti-cortisol monoclonal antibody designed to selectively bind cortisol via the (1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) and N-hydroxysulfosuccinimide (Sulfo-NHS) cross-linker. Proof of concept testing uses manually collected sweat diluted with buffer containing a fixed amount of enzyme-labeled cortisol (horseradish-peroxidase-labeled cortisol). Introducing such a sample onto the sensor leads to competitive binding between cortisol in the sweat and the enzyme-labeled cortisol. Adding hydroquinone—a molecule that reacts with enzymes on the sensor surface—produces hydrogen peroxide. An integrated wireless electronic system that applies a negative potential (−0.2 V) to the sensor leads to electrochemical reduction of the hydrogen peroxide and production of an associated current that serves as a signal with magnitude proportional to the concentration of cortisol. An integrated version of this sensor exploits microfluidic handling capabilities to allow the binding step to be performed directly while the device is on the skin. With this platform, sweat cortisol levels measured in human subjects during and post-exercise show strong correlations to corresponding concentrations in blood and saliva. These levels also exhibit expected variations associated with daily circadian rhythms, intense physical activity, and stress induced by placing a hand in cold water, where each study demonstrates different aspects of applicability in practical scenarios. Beyond the monitoring of cortisol, these systems may have broader utility in the application of sweat in biochemical monitoring of the physiological status. Specifically, the combination of graphene electrodes, immunosensing techniques, flexible electronics, and skin-compatible microfluidics have great potential in non-invasive health tracking, ranging from mental health management, military training, and human performance to cancer treatment and cardiac therapy. Combining these biochemical sensing capabilities with co-integrated systems for measuring biophysical signatures such as body temperature, heart rate, respiration rate, blood pressure, and others suggest a promising future for personalized, data-enabled health care and preventative medicine. Investigation of Cortisol Dynamics in Human Sweat Using a Graphene-Based Wireless mHealth SystemTorrente-Rodríguez et al.MatterFebruary 26, 2020In BriefA fully integrated, flexible, and miniaturized wireless mHealth sensing device based on laser-engraved graphene and immunosensing with proven utility for fast, reliable, sensitive, and non-invasive monitoring of stress hormone cortisol is developed. Pilot human study results revealed a strong correlation between sweat and circulating hormone for the first time. Both cortisol diurnal cycle and dynamic stress-response profiles were established from human sweat, reflecting the potential of such mHealth devices in personalized healthcare and human performance evaluation. Full-Text PDF Open Archive}, number={4}, journal={Matter}, publisher={Elsevier BV}, author={Bandodkar, Amay J. and Ghaffari, Roozbeh and Rogers, John A.}, year={2020}, month={Apr}, pages={795–797} }
 @article{jin_bandodkar_fratus_asadpour_rogers_alam_2020, title={Modeling, design guidelines, and detection limits of self-powered enzymatic biofuel cell-based sensors}, volume={168}, ISSN={0956-5663}, url={http://dx.doi.org/10.1016/j.bios.2020.112493}, DOI={10.1016/j.bios.2020.112493}, abstractNote={Enzymatic biofuel cell (EBFC)-based self-powered biochemical sensors obviate the need for external power sources thus enabling device miniaturization. While recent efforts driven by experimentalists illustrate the potential of EBFC-based sensors for real-time monitoring of physiologically relevant biochemicals, a robust mathematical model that quantifies the contributions of sensor components and empowers experimentalists to predict sensor performance is missing. In this paper, we provide an elegant yet simple equivalent circuit model that captures the complex, three-dimensional interplay among coupled catalytic redox reactions occurring in an EBFC-based sensor and predicts its output signal with high correlations to experimental observations. The model explains the trade-off among chemical design parameters such as the surface density of enzymes, various reaction constants as well as electrical parameters in the Butler–Volmer relationship. The model shows that the linear dynamic range and sensitivity of the EBFC-based sensor can be independently fine-tuned by changing the surface density of enzymes and electron mediators at the anode and by enhancing reductant concentrations at the cathode. The mathematical model derived in this work can be easily adapted to understand a wide range of two-electrode systems, including sensors, fuel cells, and energy storage devices.}, journal={Biosensors and Bioelectronics}, publisher={Elsevier BV}, author={Jin, Xin and Bandodkar, Amay J. and Fratus, Marco and Asadpour, Reza and Rogers, John A. and Alam, Muhammad A.}, year={2020}, month={Nov}, pages={112493} }
 @article{aranyosi_model_zhang_lee_leech_li_seib_chen_reny_wallace_et al._2020, title={Rapid Capture and Extraction of Sweat for Regional Rate and Cytokine Composition Analysis Using a Wearable Soft Microfluidic System}, volume={141}, ISSN={0022-202X}, url={http://dx.doi.org/10.1016/j.jid.2020.05.107}, DOI={10.1016/j.jid.2020.05.107}, abstractNote={Sweat is a rich, heterogeneous biofluid that consists of electrolytes (e.g., sodium, chloride, potassium ions), micronutrients (magnesium ion, calcium ion, iron, vitamin c), metabolites (e.g., glucose, lactate, ammonia, urea), hormones (e.g., cortisol, cytokines), and environmental toxins (e.g., ethanol) (Baker et al., 2009Baker L.B. Stofan J.R. Hamilton A.A. Horswill C.A. Comparison of regional patch collection vs. whole body washdown for measuring sweat sodium and potassium loss during exercise.J Appl Physiol (1985). 2009; 107: 887-895Crossref PubMed Scopus (109) Google Scholar, Baker and Wolfe, 2020Baker L.B. Wolfe A.S. Physiological mechanisms determining eccrine sweat composition.Eur J Appl Physiol. 2020; 120: 719-752Crossref PubMed Scopus (36) Google Scholar). Biomarkers in sweat provide insight about underlying physiological and metabolic processes and exhibit changes related to performance, wellness, and health (Baker and Wolfe, 2020Baker L.B. Wolfe A.S. Physiological mechanisms determining eccrine sweat composition.Eur J Appl Physiol. 2020; 120: 719-752Crossref PubMed Scopus (36) Google Scholar). For example, sweat chloride testing is a well-established and routine clinical tool for cystic fibrosis screening in newborns (Gibson and Cooke, 1959Gibson L.E. Cooke R.E. A test for concentration of electrolytes in sweat in cystic fibrosis of the pancreas utilizing pilocarpine by iontophoresis.Pediatrics. 1959; 23: 545-549PubMed Google Scholar, Mishra et al., 2005Mishra A. Greaves R. Massie J. The relevance of sweat testing for the diagnosis of cystic fibrosis in the genomic era.Clin Biochem Rev. 2005; 26: 135-153PubMed Google Scholar). More recently, several studies have demonstrated the efficacy and potential of sweat as a target for monitoring drug levels (e.g., levodopa) for therapeutic dosing (Tai et al., 2019Tai L.C. Liaw T.S. Lin Y. Nyein H.Y.Y. Bariya M. Ji W. et al.Wearable sweat band for noninvasive levodopa monitoring.Nano Lett. 2019; 19: 6346-6351Crossref PubMed Scopus (50) Google Scholar), sweat glucose screening in diabetes management (Lee et al., 2017Lee H. Song C. Hong Y.S. Kim M.S. Cho H.R. Kang T. et al.Wearable/disposable sweat-based glucose monitoring device with multistage transdermal drug delivery module.Sci Adv. 2017; 3e1601314Crossref PubMed Scopus (510) Google Scholar), ethanol levels to assess alcohol intoxication (Gamella et al., 2014Gamella M. Campuzano S. Manso J. González de Rivera G. López-Colino F. Reviejo A.J. et al.A novel non-invasive electrochemical biosensing device for in situ determination of the alcohol content in blood by monitoring ethanol in sweat.Anal Chim Acta. 2014; 806: 1-7Crossref PubMed Scopus (81) Google Scholar), cortisol levels to monitor stress (Torrente-Rodríguez et al., 2020Torrente-Rodríguez R.M. Tu J. Yang Y. Min J. Wang M. Song Y. et al.Investigation of cortisol dynamics in human sweat using a graphene-based wireless mHealth system.Matter. 2020; 2: 921-937Abstract Full Text Full Text PDF PubMed Scopus (87) Google Scholar), and lactate concentrations to track hypoxia (Pribil et al., 2014Pribil M.M. Laptev G.U. Karyakina E.E. Karyakin A.A. Noninvasive hypoxia monitor based on gene-free engineering of lactate oxidase for analysis of undiluted sweat.Anal Chem. 2014; 86: 5215-5219Crossref PubMed Scopus (39) Google Scholar). Quantitative analysis of sweat composition and dynamics currently relies on, first, capturing the sweat using disposable gauzes, absorbent pads, or microtubes followed by sample extraction through centrifuge and gravimetric tools and, finally, off-site analysis of the collected samples by leveraging standard laboratory-based analytical techniques. Of these, the sweat collection and extraction steps are most prone to introducing errors arising from sample contamination, evaporation, and spillage, which affects measurement accuracy, especially for the analysis of small proteins and cytokines in sweat (Dai et al., 2013Dai X. Okazaki H. Hanakawa Y. Murakami M. Tohyama M. Shirakata Y. et al.Eccrine sweat contains IL-1α, IL-1β and IL-31 and activates epidermal keratinocytes as a danger signal.PLoS One. 2013; 8e67666Crossref PubMed Scopus (53) Google Scholar, Katchman et al., 2018Katchman B.A. Zhu M. Blain Christen J. Anderson K.S. Eccrine sweat as a biofluid for profiling immune biomarkers.Proteomics Clin Appl. 2018; 12e1800010Crossref PubMed Scopus (29) Google Scholar). Thus, there is a critical need for uncomplicated and accurate wearable devices that can readily capture sweat in a point-of-care setting (Choi et al., 2018Choi J. Ghaffari R. Baker L.B. Rogers J.A. Skin-interfaced systems for sweat collection and analytics.Sci Adv. 2018; 4: eaar3921Crossref PubMed Scopus (184) Google Scholar, Ray et al., 2019Ray T.R. Choi J. Bandodkar A.J. Krishnan S. Gutruf P. Tian L. et al.Bio-integrated wearable systems: a comprehensive review.Chem Rev. 2019; 119: 5461-5533Crossref PubMed Scopus (369) Google Scholar). Here, we present a soft, skin-interfaced microfluidic patch that facilitates rapid capture and clean extraction of precise volumes of sweat into quantifiable volumes for cytokine analysis. The microfluidic patches were skin mounted on healthy subjects (n = 10) to collect excreted sweat during exposure to heat (40–45 °C) in a controlled environment chamber. The study protocol was approved by the Institutional Review Board of Northwestern University (Evanston, IL) (IRB:STU00208494). Written informed consent was obtained for all subjects. Concentrations of cytokines IL-1α, IL-1RA, and IL-8 were measured across three regions of the arms for each subject diurnally (morning and evening measurements) and on consecutive days (Supplementary Figure S1). These cytokines were chosen because of their direct relevance to inflammatory responses in patients with atopic dermatitis. Sweat samples were analyzed with an immunoassay, thereby introducing a robust wearable platform for tracking sweat rate and inflammation cytokines found in sweat. Soft, wearable microfluidic devices and extraction platforms serve as a collection, storage, extraction, and measurement system that is well-suited for intimate skin coupling and rapid analysis of biofluids in remote settings. The soft wearable device mounts directly on the skin to achieve a water-tight seal. Figure 1a and Supplementary Figure S2 show an exploded view of the multilayered device, highlighting the intricate geometry and ultrathin, impermeable microchannel layers. This six-layer polymeric design is ultrathin and impermeable to external gases, thereby limiting evaporation over several days. This unique material design is ideal for remote clinical trial and at-home settings, where biosamples may require storage for several hours or days in the absence of biofluid handling equipment. The skin adhesion layer lies on the bottom surface of the device and incorporates a small collection area that facilitates the flow of sweat into an inlet port, which in turn connects to the overlying microchannel. The inlet port is limited in size (1–2 mm), which significantly limits contamination issues owing to sweat-to-skin contact prevalent with more conventional sweat collection devices. Sweat entering the inlet area propagates through the microchannel where it is captured (Figure 1b and c). The length and cross-sectional geometry of the microchannel determine the total volume of sweat captured and sweat rate over a given sweat-collection session. Figure 1d shows three microfluidic patches skin mounted on the forearms of a subject. The magnified view in Figure 1d highlights the key physical features of the patch on the epidermis (e.g., microchannel, inlet port, outlet port) and the real-time flow of sweat through the microchannel in a way that is visible to clinical staff. The extraction platform is used to rapidly extract the collected sweat samples into cryovials for analysis, without requiring a centrifuge and other expensive handling equipment (Figure 1e and f and Supplementary Figure S3). To test the sweat rate dependence of cytokine concentrations, we quantified the volume of sweat collected for each sample. The volumetric range of sweat extracted across multiple subjects was 10–233 μl. Linear regression analysis demonstrates that the volume of collected sweat does not correlate with concentrations of IL-1α (y = −7.96× + 2,762; adjusted R2 = 0.08166) or IL-1RA (y = −5.97× + 3,449; adjusted R2 = −0.001975) (Figure 2a). Furthermore, linear regression analysis was conducted for sweat volume and IL-8 (y = −0.0030× + 1.425; adjusted R2 = 0.0720); however, the concentrations of IL-8 in sweat in healthy subjects were near the detection limit of the assay, thereby making a correlation difficult to assess in healthy subjects. These volume-versus-concentration results indicate that IL-1α and IL-RA concentrations are independent of sweat rate across the forearm regions of the body in healthy subjects. Because cytokine concentrations in blood plasma have been shown to vary with diurnal cycles (Petrovsky et al., 1998Petrovsky N. McNair P. Harrison L.C. Diurnal rhythms of pro-inflammatory cytokines: regulation by plasma cortisol and therapeutic implications.Cytokine. 1998; 10: 307-312Crossref PubMed Scopus (226) Google Scholar, Vgontzas et al., 2005Vgontzas A.N. Bixler E.O. Lin H.M. Prolo P. Trakada G. Chrousos G.P. IL-6 and its circadian secretion in humans.Neuroimmunomodulation. 2005; 12: 131-140Crossref PubMed Scopus (247) Google Scholar), we investigated whether a similar phenomenon could be observed with sweat cytokines. Concentrations of IL-1α and IL-1RA were pooled across three anatomic regions (upper left forearm and bilateral lower forearms) and subgrouped by the time of collection (Figure 2b). For sweat samples that were collected during the morning, the median and SD of IL-1α, IL-1RA, and IL-8 concentrations were 789 ± 1,599, 2,639 ± 2,797, and 0.92 ± 0.86 pg/ml, respectively. Concentrations of IL-1α were comparable with those measured using other sweat collection methods (Dai et al., 2013Dai X. Okazaki H. Hanakawa Y. Murakami M. Tohyama M. Shirakata Y. et al.Eccrine sweat contains IL-1α, IL-1β and IL-31 and activates epidermal keratinocytes as a danger signal.PLoS One. 2013; 8e67666Crossref PubMed Scopus (53) Google Scholar, Katchman et al., 2018Katchman B.A. Zhu M. Blain Christen J. Anderson K.S. Eccrine sweat as a biofluid for profiling immune biomarkers.Proteomics Clin Appl. 2018; 12e1800010Crossref PubMed Scopus (29) Google Scholar). For sweat samples that were collected during the evening, the median and SD of IL-1α, IL-1RA, and IL-8 concentrations were 2,639 ± 1,432, 2,340 ± 3,021, and 1.02 ± 0.25 pg/ml, respectively. Wilcoxon rank-sum tests were conducted to compare the cytokine concentrations between morning and evening sample collections. The differences between morning and evening measurements were statistically significant for IL-1α (P = 0.0052) and IL-1RA (P = 0.042), whereas IL-8 (P = 0.59) measurements were not. Unlike plasma, sweat composition could vary with anatomic location (Baker et al., 2009Baker L.B. Stofan J.R. Hamilton A.A. Horswill C.A. Comparison of regional patch collection vs. whole body washdown for measuring sweat sodium and potassium loss during exercise.J Appl Physiol (1985). 2009; 107: 887-895Crossref PubMed Scopus (109) Google Scholar). We analyzed the location dependence of sweat samples collected in the morning and the evening from the different arm locations (Figure 2c). Kruskal–Wallis ANOVA tests demonstrated no significant differences in sweat cytokines collected from the left lower arm, right arm, or upper left arm for both IL-1α (morning: P = 0.58; evening: P = 0.97) and IL-1RA (morning: P = 0.78; evening: P = 0.81). The results of Figure 2 provide insight into the origins of IL-1α and IL-1RA in sweat. The relative independence of cytokine concentrations on sweat rate suggests that the cytokines are present in the sweat produced by the sweat glands rather than dissolved into sweat after being produced by another mechanism (e.g., keratinocytes). This in turn suggests a correlation between cytokine levels in sweat, interstitial fluid, and plasma, providing a potential noninvasive way to track changes in plasma cytokine levels. The presence of such correlation needs to be established through direct measurements. The lack of dependence on anatomic collection location (Figure 2c) and consistency across days (Supplementary Figure S1) indicate that cytokine concentrations are consistent over days and locations in healthy subjects but could vary with time of day for a given subject (Figure 2b). The relative increases in IL-1α and IL-1RA concentrations in the evening compared with those in the morning indicate diurnal fluctuations in sweat cytokine levels, consistent with previous studies of cytokine plasma and sweat cytokine levels (Katchman et al., 2018Katchman B.A. Zhu M. Blain Christen J. Anderson K.S. Eccrine sweat as a biofluid for profiling immune biomarkers.Proteomics Clin Appl. 2018; 12e1800010Crossref PubMed Scopus (29) Google Scholar, Petrovsky et al., 1998Petrovsky N. McNair P. Harrison L.C. Diurnal rhythms of pro-inflammatory cytokines: regulation by plasma cortisol and therapeutic implications.Cytokine. 1998; 10: 307-312Crossref PubMed Scopus (226) Google Scholar, Vgontzas et al., 2005Vgontzas A.N. Bixler E.O. Lin H.M. Prolo P. Trakada G. Chrousos G.P. IL-6 and its circadian secretion in humans.Neuroimmunomodulation. 2005; 12: 131-140Crossref PubMed Scopus (247) Google Scholar). Whether such fluctuations serve a skin-specific role or simply reflect variations in plasma concentrations, requires additional testing across larger populations and different disease subgroups, including atopic dermatitis, urticaria, hyperhidrosis, and other autonomic thermal regulation disorders. The data that support the plots within this paper and other findings of this study are available from the corresponding author upon reasonable request. Jeffrey B. Model: http://orcid.org/0000-0003-3052-7076 Michael Z. Zhang: http://orcid.org/0000-0002-7485-8101 Adam Leech: http://orcid.org/0000-0003-3943-1097 Weihua Li: http://orcid.org/0000-0001-5660-5082 Melissa S. Seib: http://orcid.org/0000-0002-9528-0118 Shulin Chen: http://orcid.org/0000-0002-0280-1536 Jessica Wallace: http://orcid.org/0000-0002-2654-7149 Michael H. Shin: http://orcid.org/0000-0002-8803-6862 Amay J. Bandodkar: http://orcid.org/0000-0002-1792-1506 Jungil Choi: http://orcid.org/0000-0002-3659-8978 Amy S. Paller: http://orcid.org/0000-0001-6187-6549 John A. Rogers: http://orcid.org/0000-0002-2980-3961 Shaui Xu: http://orcid.org/0000-0003-3560-6945 AJA, JBM, SPL, AL, WL, NR, MSS, SC, JW, JAR, and RG are cofounders and/or employees of Epicore Biosystems, Cambridge, MA, a company that pursues commercialization of microfluidic devices for wearable applications. The remaining authors state no conflict of interest. This research was funded by LEO Science & Tech Hub . This work utilized the Northwestern University Micro/Nano Fabrication Facility. Conceptualization: AJA, JBM, SPL, JAR, ASP, SX, RG; Data Curation: AJA, MZZ, SPL; Formal Analysis: AJA, MZZ, SPL, RG; Investigation: WL, SC, JC, AJA, MSS, SPL, AJB, RG; Methodology: JBM, AL, NR, JW; Writing - Original Draft Preparation: AJA, MZZ, RG; Writing - Review and Editing: AJA, JBM, SPL, NR, MZZ, MSS, AJB, JW, JAR, ASP, SX, RG Sweat was collected from subjects (n = 10) over a 30–45 minutes period on each of two consecutive days (Supplementary Figure S1). For six of these subjects, the collection was conducted at around the same time each day (five in the morning, one in the evening). For the others, sweat was collected during a morning session and evening session. A custom-built microfluidic patch (Supplementary Figure S2a) designed to collect up to ∼200 μl of sweat, with minimal evaporation (Supplementary Figure S2b), was applied to the epidermis at multiple anatomic positions on the arms. Subjects’ left and right inner volar forearms were examined to ensure that they had intact skin. Subjects with excessive hair in patch application areas had this hair trimmed. The left and right volar forearms were cleaned with sterile alcohol wipes and allowed to dry. Three microfluidic patches were applied to the left proximal, left distal, and right proximal volar forearms (Figure 1d). Subjects entered a sauna to induce sweating. They were allowed to enter and leave ad libitum until 45 minutes had expired or the patches were filled to at least 50 μl, whichever came first. For the first three subjects, sweat was collected until the patches were completely full to ensure that sufficient sweat was available for assay development. Times of patch application and each sauna entry and exit were recorded. Once subjects exited the sauna, patches were removed one at a time and placed on a sweat extraction fixture (Supplementary Figure S3a–c). The exit port of the patch was gently cleaned with an alcohol wipe and positioned over the inlet of a labeled cryovial. Positive pressure applied to the fixture pushed sweat through the channel, out of the exit port and into the cryovial (Supplementary Figure S3d). After closing the vial, the patch was removed and discarded, and the extraction fixture was cleaned with an alcohol wipe. This process was repeated for all patches and subjects for a given collection group. To determine collected sweat volume, a scale was zeroed with an empty cryovial and the differential weight of each filled vial was measured. When the fluid volume was very low (∼15 μl or less), the resulting weight was sometimes zero or negative owing to variation among the vials. Protease and phosphatase inhibitor cocktails were each added at 10% v/v. Vials were then vortexed and stored at −80 °C. When all subject samples had been collected and prepared, the samples were shipped overnight on dry ice to a bioassay laboratory (Pacific BioLabs, Hercules, CA) for analysis. Sweat was analyzed using U-PLEX assay kits (Meso Scale Diagnostics, Rockville, MD). Because these kits were not designed specifically for sweat, a series of spike-recovery tests were performed to refine and validate the measurement process. For the resulting process, the samples were rapidly thawed and centrifuged. The supernatant was extracted and diluted in the ratio of 1:2 in PBS to raise the pH. The samples were then processed following the instructions in the kit. Subject samples were analyzed following this same process. Three subjects had sweat samples collected during both morning and evening, and the cytokine concentrations were directly compared. In all cases, concentrations of IL-1α and IL-1RA from samples collected in the evening were higher for a given subject. Mean ratios (evening to morning) were 4.2 for IL-1α (range 1.4–5.8) and 4.6 for IL-1RA (range 2.7–5.5). In one subject from whom three samples were collected, concentrations rose from morning to evening on the first day, then fell again the following morning (IL-1α: 857–3,982–603 pg/ml; IL-1RA: 733–3,267–456 pg/ml). To explore the repeatability of sweat cytokine measurements, samples were collected from each subject on two sequential days. For the purpose of this comparison, only samples collected at the same time of the day (both in the morning or both in the evening) were included. Supplementary Figure S1 shows that IL-1α and IL-1RA concentrations were highly correlated across days for healthy subjects. However, the slope of the linear regression fit for IL-1α was less than one (∼0.57), indicating a shift in concentrations by a factor of ∼2 across a small sample size.}, number={2}, journal={Journal of Investigative Dermatology}, publisher={Elsevier BV}, author={Aranyosi, Alexander J. and Model, Jeffrey B. and Zhang, Michael Z. and Lee, Stephen P. and Leech, Adam and Li, Weihua and Seib, Melissa S. and Chen, Shulin and Reny, Nikolas and Wallace, Jessica and et al.}, year={2020}, month={Jun}, pages={433–437.e3} }
 @article{vázquez-guardado_yang_bandodkar_rogers_2020, title={Recent advances in neurotechnologies with broad potential for neuroscience research}, volume={23}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85096055262&partnerID=MN8TOARS}, DOI={10.1038/s41593-020-00739-8}, abstractNote={Interest in deciphering the fundamental mechanisms and processes of the human mind represents a central driving force in modern neuroscience research. Activities in support of this goal rely on advanced methodologies and engineering systems that are capable of interrogating and stimulating neural pathways, from single cells in small networks to interconnections that span the entire brain. Recent research establishes the foundations for a broad range of creative neurotechnologies that enable unique modes of operation in this context. This review focuses on those systems with proven utility in animal model studies and with levels of technical maturity that suggest a potential for broad deployment to the neuroscience community in the relatively near future. We include a brief summary of existing and emerging neuroscience techniques, as background for a primary focus on device technologies that address associated opportunities in electrical, optical and microfluidic neural interfaces, some with multimodal capabilities. Examples of the use of these technologies in recent neuroscience studies illustrate their practical value. The vibrancy of the engineering science associated with these platforms, the interdisciplinary nature of this field of research and its relevance to grand challenges in the treatment of neurological disorders motivate continued growth of this area of study.}, number={12}, journal={Nature Neuroscience}, publisher={Springer Science and Business Media LLC}, author={Vázquez-Guardado, Abraham and Yang, Yiyuan and Bandodkar, Amay J. and Rogers, John A.}, year={2020}, pages={1522–1536} }
 @article{hourlier-fargette_schon_xue_avila_li_gao_liu_kim_raj_fields_et al._2020, title={Skin-interfaced soft microfluidic systems with modular and reusable electronics for: In situ capacitive sensing of sweat loss, rate and conductivity}, volume={20}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85096888147&partnerID=MN8TOARS}, DOI={10.1039/d0lc00705f}, abstractNote={Stick-on electrodes capacitively coupled to single-use microfluidic channels enable contactless analysis of sweat in a soft wearable format with real-time wireless data collection.}, number={23}, journal={Lab on a Chip}, author={Hourlier-Fargette, A. and Schon, S. and Xue, Y. and Avila, R. and Li, W. and Gao, Y. and Liu, C. and Kim, S.B. and Raj, M.S. and Fields, K.B. and et al.}, year={2020}, pages={4391–4403} }
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 @article{koo_kim_choi_xie_bandodkar_khalifeh_yan_kim_pezhouh_doty_et al._2020, title={Wirelessly controlled, bioresorbable drug delivery device with active valves that exploit electrochemically triggered crevice corrosion}, volume={6}, ISSN={2375-2548}, url={http://dx.doi.org/10.1126/sciadv.abb1093}, DOI={10.1126/sciadv.abb1093}, abstractNote={Bioresorbable drug release platforms offer advanced treatment for hormone imbalances, malignant cancers, and diabetic conditions.}, number={35}, journal={Science Advances}, publisher={American Association for the Advancement of Science (AAAS)}, author={Koo, Jahyun and Kim, Sung Bong and Choi, Yeon Sik and Xie, Zhaoqian and Bandodkar, Amay J. and Khalifeh, Jawad and Yan, Ying and Kim, Hojun and Pezhouh, Maryam Kherad and Doty, Karen and et al.}, year={2020}, month={Aug}, pages={eabb1093} }
 @article{bandodkar_gutruf_choi_lee_sekine_reeder_jeang_aranyosi_lee_model_et al._2019, title={Battery-free, skin-interfaced microfluidic/electronic systems for simultaneous electrochemical, colorimetric, and volumetric analysis of sweat}, volume={5}, ISSN={2375-2548}, url={http://dx.doi.org/10.1126/sciadv.aav3294}, DOI={10.1126/sciadv.aav3294}, abstractNote={Battery-free, wireless microfluidic/electronic system for multiparameter sweat analysis.}, number={1}, journal={Science Advances}, publisher={American Association for the Advancement of Science (AAAS)}, author={Bandodkar, Amay J. and Gutruf, Philipp and Choi, Jungil and Lee, KunHyuck and Sekine, Yurina and Reeder, Jonathan T. and Jeang, William J. and Aranyosi, Alexander J. and Lee, Stephen P. and Model, Jeffrey B. and et al.}, year={2019}, month={Jan}, pages={eaav3294} }
 @article{ray_choi_bandodkar_krishnan_gutruf_tian_ghaffari_rogers_2019, title={Bio-Integrated Wearable Systems: A Comprehensive Review}, volume={119}, ISSN={0009-2665 1520-6890}, url={http://dx.doi.org/10.1021/acs.chemrev.8b00573}, DOI={10.1021/acs.chemrev.8b00573}, abstractNote={Bio-integrated wearable systems can measure a broad range of biophysical, biochemical, and environmental signals to provide critical insights into overall health status and to quantify human performance. Recent advances in material science, chemical analysis techniques, device designs, and assembly methods form the foundations for a uniquely differentiated type of wearable technology, characterized by noninvasive, intimate integration with the soft, curved, time-dynamic surfaces of the body. This review summarizes the latest advances in this emerging field of "bio-integrated" technologies in a comprehensive manner that connects fundamental developments in chemistry, material science, and engineering with sensing technologies that have the potential for widespread deployment and societal benefit in human health care. An introduction to the chemistries and materials for the active components of these systems contextualizes essential design considerations for sensors and associated platforms that appear in following sections. The subsequent content highlights the most advanced biosensors, classified according to their ability to capture biophysical, biochemical, and environmental information. Additional sections feature schemes for electrically powering these sensors and strategies for achieving fully integrated, wireless systems. The review concludes with an overview of key remaining challenges and a summary of opportunities where advances in materials chemistry will be critically important for continued progress.}, number={8}, journal={Chemical Reviews}, publisher={American Chemical Society (ACS)}, author={Ray, Tyler R. and Choi, Jungil and Bandodkar, Amay J. and Krishnan, Siddharth and Gutruf, Philipp and Tian, Limei and Ghaffari, Roozbeh and Rogers, John A.}, year={2019}, month={Jan}, pages={5461–5533} }
 @article{zhao_guo_li_bandodkar_rogers_2019, title={Body-Interfaced Chemical Sensors for Noninvasive Monitoring and Analysis of Biofluids}, volume={1}, ISSN={2589-5974}, url={http://dx.doi.org/10.1016/j.trechm.2019.07.001}, DOI={10.1016/j.trechm.2019.07.001}, abstractNote={Body-interfaced chemical sensors allow for continuous, noninvasive collection, storage, and analysis of underexplored classes of biofluids, including sweat, tears, saliva, and interstitial fluid. Different sensing modalities and advanced materials/device designs improve the stability, selectivity, and sensitivity of these body-interfaced sensors. Multimodal platforms that combine physical and chemical sensing capabilities with wireless functionality are promising for precise, clinical-grade assessments of health status and disease conditions outside of hospital or laboratory settings. Body-interfaced sensors have received tremendous attention due to a broad and diverse collection of potential applications, from monitoring of health status to managing and preventing disease conditions. In this review article, we highlight the emerging sensing modalities and advanced materials/device designs in body-integrated flexible platforms capable of capturing and analyzing biofluids. In particular, we discuss different chemical sensors and biosensors for real-time noninvasive monitoring and analysis of metabolites and electrolytes in sweat, tears, saliva, and interstitial fluid. Finally, we show several techniques that could be integrated with body-interfaced sensors for data acquisition, signal processing, display, and communication. Body-interfaced sensors have received tremendous attention due to a broad and diverse collection of potential applications, from monitoring of health status to managing and preventing disease conditions. In this review article, we highlight the emerging sensing modalities and advanced materials/device designs in body-integrated flexible platforms capable of capturing and analyzing biofluids. In particular, we discuss different chemical sensors and biosensors for real-time noninvasive monitoring and analysis of metabolites and electrolytes in sweat, tears, saliva, and interstitial fluid. Finally, we show several techniques that could be integrated with body-interfaced sensors for data acquisition, signal processing, display, and communication. an electrochemical technique that measures current generated from the oxidation or reduction of an electroactive analyte in a chemical reaction. a solution that bathes and surrounds the cells. a zero-current technique that measures the potential appearing between the working electrode and the reference electrode in an electrochemical cell. a voltammetric method that involves (i) preconcentration of the analyte of interest on the electrode surface and (ii) selective oxidation during the stripping step. a technique that involves passing a current across two electrodes applied to the skin. This causes electro-osmotic flow of the metabolites from the subcutaneous layer to surface of the skin.}, number={6}, journal={Trends in Chemistry}, publisher={Elsevier BV}, author={Zhao, Jie and Guo, Hexia and Li, Jinghua and Bandodkar, Amay J. and Rogers, John A.}, year={2019}, month={Sep}, pages={559–571} }
 @book{wang_bandodkar_2019, title={Multiple-use renewable electrochemical sensors based on direct drawing of enzymatic inks}, number={10,501,770}, author={Wang, Joseph and Bandodkar, Amay Jairaj}, year={2019}, month={Dec} }
 @article{zhang_guo_kim_wu_ostojich_park_wang_weng_li_bandodkar_et al._2019, title={Passive sweat collection and colorimetric analysis of biomarkers relevant to kidney disorders using a soft microfluidic system}, volume={19}, ISSN={1473-0197 1473-0189}, url={http://dx.doi.org/10.1039/c9lc00103d}, DOI={10.1039/c9lc00103d}, abstractNote={Passive sweat collection and colorimetric analysis.}, number={9}, journal={Lab on a Chip}, publisher={Royal Society of Chemistry (RSC)}, author={Zhang, Yi and Guo, Hexia and Kim, Sung Bong and Wu, Yixin and Ostojich, Diana and Park, Sook Hyeon and Wang, Xueju and Weng, Zhengyan and Li, Rui and Bandodkar, Amay J. and et al.}, year={2019}, pages={1545–1555} }
 @book{wang_bandodkar_2019, title={Printed flexible electronic devices containing self-repairing structures}, url={https://patents.google.com/patent/US20190237228A1/en}, number={20190237228A1}, author={Wang, Joseph and Bandodkar, Amay Jairaj}, year={2019} }
 @article{reeder_xue_franklin_deng_choi_prado_kim_liu_hanson_ciraldo_et al._2019, title={Resettable skin interfaced microfluidic sweat collection devices with chemesthetic hydration feedback}, volume={10}, ISSN={2041-1723}, url={http://dx.doi.org/10.1038/s41467-019-13431-8}, DOI={10.1038/s41467-019-13431-8}, abstractNote={Abstract}, number={1}, journal={Nature Communications}, publisher={Springer Science and Business Media LLC}, author={Reeder, Jonathan T. and Xue, Yeguang and Franklin, Daniel and Deng, Yujun and Choi, Jungil and Prado, Olivia and Kim, Robin and Liu, Claire and Hanson, Justin and Ciraldo, John and et al.}, year={2019}, month={Dec} }
 @article{choi_bandodkar_reeder_ray_turnquist_kim_nyberg_hourlier-fargette_model_aranyosi_et al._2019, title={Soft, Skin-Integrated Multifunctional Microfluidic Systems for Accurate Colorimetric Analysis of Sweat Biomarkers and Temperature}, volume={4}, ISSN={2379-3694 2379-3694}, url={http://dx.doi.org/10.1021/acssensors.8b01218}, DOI={10.1021/acssensors.8b01218}, abstractNote={Real-time measurements of the total loss of sweat, the rate of sweating, the temperature of sweat, and the concentrations of electrolytes and metabolites in sweat can provide important insights into human physiology. Conventional methods use manual collection processes (e.g., absorbent pads) to determine sweat loss and lab-based instrumentation to analyze its chemical composition. Although such schemes can yield accurate data, they cannot be used outside of laboratories or clinics. Recently reported wearable electrochemical devices for sweat sensing bypass these limitations, but they typically involve on-board electronics, electrodes, and/or batteries for measurement, signal processing, and wireless transmission, without direct means for measuring sweat loss or capturing and storing small volumes of sweat. Alternative approaches exploit soft, skin-integrated microfluidic systems for collection and colorimetric chemical techniques for analysis. Here, we present the most advanced platforms of this type, in which optimized chemistries, microfluidic designs, and device layouts enable accurate assessments not only of total loss of sweat and sweat rate but also of quantitatively accurate values of the pH and temperature of sweat, and of the concentrations of chloride, glucose, and lactate across physiologically relevant ranges. Color calibration markings integrated into a graphics overlayer allow precise readout by digital image analysis, applicable in various lighting conditions. Field studies conducted on healthy volunteers demonstrate the full capabilities in measuring sweat loss/rate and analyzing multiple sweat biomarkers and temperature, with performance that quantitatively matches that of conventional lab-based measurement systems.}, number={2}, journal={ACS Sensors}, publisher={American Chemical Society (ACS)}, author={Choi, Jungil and Bandodkar, Amay J. and Reeder, Jonathan T. and Ray, Tyler R. and Turnquist, Amelia and Kim, Sung Bong and Nyberg, Nathaniel and Hourlier-Fargette, Aurélie and Model, Jeffrey B. and Aranyosi, Alexander J. and et al.}, year={2019}, month={Feb}, pages={379–388} }
 @article{bandodkar_choi_lee_jeang_agyare_gutruf_wang_sponenburg_reeder_schon_et al._2019, title={Soft, Skin-Interfaced Microfluidic Systems with Passive Galvanic Stopwatches for Precise Chronometric Sampling of Sweat}, volume={31}, ISSN={0935-9648}, url={http://dx.doi.org/10.1002/adma.201902109}, DOI={10.1002/adma.201902109}, abstractNote={Abstract}, number={32}, journal={Advanced Materials}, publisher={Wiley}, author={Bandodkar, Amay J. and Choi, Jungil and Lee, Stephen P. and Jeang, William J. and Agyare, Prophecy and Gutruf, Philipp and Wang, Siqing and Sponenburg, Rebecca A. and Reeder, Jonathan T. and Schon, Stephanie and et al.}, year={2019}, month={Jun}, pages={1902109} }
 @inproceedings{bandodkar_2019, title={Soft, skin-interfaced, wireless, battery-free, microfluidic devices for chronometric sweat capture and analysis}, volume={31}, number={32}, booktitle={Abstracts of Papers of the American Chemical Society}, author={Bandodkar, Amay}, year={2019}, month={Jun}, pages={258} }
 @article{reeder_choi_xue_gutruf_hanson_liu_ray_bandodkar_avila_xia_et al._2019, title={Waterproof, electronics-enabled, epidermal microfluidic devices for sweat collection, biomarker analysis, and thermography in aquatic settings}, volume={5}, ISSN={2375-2548}, url={http://dx.doi.org/10.1126/sciadv.aau6356}, DOI={10.1126/sciadv.aau6356}, abstractNote={Waterproof epidermal microfluidics enable collection and analysis of sweat during aquatic exercise.}, number={1}, journal={Science Advances}, publisher={American Association for the Advancement of Science (AAAS)}, author={Reeder, Jonathan T. and Choi, Jungil and Xue, Yeguang and Gutruf, Philipp and Hanson, Justin and Liu, Mark and Ray, Tyler and Bandodkar, Amay J. and Avila, Raudel and Xia, Wei and et al.}, year={2019}, month={Jan}, pages={eaau6356} }
 @article{bandodkar_jeang_ghaffari_rogers_2019, title={Wearable Sensors for Biochemical Sweat Analysis}, volume={12}, ISSN={1936-1327 1936-1335}, url={http://dx.doi.org/10.1146/annurev-anchem-061318-114910}, DOI={10.1146/annurev-anchem-061318-114910}, abstractNote={Sweat is a largely unexplored biofluid that contains many important biomarkers ranging from electrolytes and metabolites to proteins, cytokines, antigens, and exogenous drugs. The eccrine and apocrine glands produce and excrete sweat through microscale pores on the epidermal surface, offering a noninvasive means for capturing and probing biomarkers that reflect hydration state, fatigue, nutrition, and physiological changes. Recent advances in skin-interfaced wearable sensors capable of real-time in situ sweat collection and analytics provide capabilities for continuous biochemical monitoring in an ambulatory mode of operation. This review presents a broad overview of sweat-based biochemical sensor technologies with an emphasis on enabling materials, designs, and target analytes of interest. The article concludes with a summary of challenges and opportunities for researchers and clinicians in this swiftly growing field.}, number={1}, journal={Annual Review of Analytical Chemistry}, publisher={Annual Reviews}, author={Bandodkar, Amay J. and Jeang, William J. and Ghaffari, Roozbeh and Rogers, John A.}, year={2019}, month={Jun}, pages={1–22} }
 @article{sekine_kim_zhang_bandodkar_xu_choi_irie_ray_kohli_kozai_et al._2018, title={A fluorometric skin-interfaced microfluidic device and smartphone imaging module for in situ quantitative analysis of sweat chemistry}, volume={18}, ISSN={1473-0197 1473-0189}, url={http://dx.doi.org/10.1039/c8lc00530c}, DOI={10.1039/c8lc00530c}, abstractNote={A wearable microfluidic system and smartphone optics module enabled in situ analysis of sweat.}, number={15}, journal={Lab on a Chip}, publisher={Royal Society of Chemistry (RSC)}, author={Sekine, Yurina and Kim, Sung Bong and Zhang, Yi and Bandodkar, Amay J. and Xu, Shuai and Choi, Jungil and Irie, Masahiro and Ray, Tyler R. and Kohli, Punit and Kozai, Naofumi and et al.}, year={2018}, pages={2178–2186} }
 @article{bandodkar_imani_nuñez-flores_kumar_wang_mohan_wang_mercier_2018, title={Re-usable electrochemical glucose sensors integrated into a smartphone platform}, volume={101}, ISSN={0956-5663}, url={http://dx.doi.org/10.1016/j.bios.2017.10.019}, DOI={10.1016/j.bios.2017.10.019}, abstractNote={This article demonstrates a new smartphone-based reusable glucose meter. The glucose meter includes a custom-built smartphone case that houses a permanent bare sensor strip, a stylus that is loaded with enzyme-carbon composite pellets, and sensor instrumentation circuits. A custom-designed Android-based software application was developed to enable easy and clear display of measured glucose concentration. A typical test involves the user loading the software, using the stylus to dispense an enzymatic pellet on top of the bare sensor strip affixed to the case, and then introducing the sample. The electronic module then acquires and wirelessly transmits the data to the application software to be displayed on the screen. The deployed pellet is then discarded to regain the fresh bare sensor surface. Such a unique working principle allows the system to overcome challenges faced by previously reported reusable sensors, such as enzyme degradation, leaching, and hysteresis effects. Studies reveal that the enzyme loaded in the pellets are stable for up to 8 months at ambient conditions, and generate reproducible sensor signals. The work illustrates the significance of the pellet-based sensing system towards realizing a reusable, point-of-care sensor that snugly fits around a smartphone and which does not face issues usually common to reusable sensors. The versatility of this system allows it to be easily modified to detect other analytes for application in a wide range of healthcare, environmental and defense domains.}, journal={Biosensors and Bioelectronics}, publisher={Elsevier BV}, author={Bandodkar, Amay J. and Imani, Somayeh and Nuñez-Flores, Rogelio and Kumar, Rajan and Wang, Chiyi and Mohan, A.M. Vinu and Wang, Joseph and Mercier, Patrick P.}, year={2018}, month={Mar}, pages={181–187} }
 @article{kim_lee_raj_lee_reeder_koo_hourlier-fargette_bandodkar_won_sekine_et al._2018, title={Soft, Skin-Interfaced Microfluidic Systems with Wireless, Battery-Free Electronics for Digital, Real-Time Tracking of Sweat Loss and Electrolyte Composition}, volume={14}, ISSN={1613-6810}, url={http://dx.doi.org/10.1002/smll.201802876}, DOI={10.1002/smll.201802876}, abstractNote={Abstract}, number={45}, journal={Small}, publisher={Wiley}, author={Kim, Sung Bong and Lee, KunHyuck and Raj, Milan S. and Lee, Boram and Reeder, Jonathan T. and Koo, Jahyun and Hourlier-Fargette, Aurélie and Bandodkar, Amay J. and Won, Sang Min and Sekine, Yurina and et al.}, year={2018}, month={Oct}, pages={1802876} }
 @inproceedings{bandodkar_wang_rogers_2018, title={Soft, Stretchable Wearable Platforms for Sensing and Energy Harvesting Applications}, ISBN={978-0-8169-1108-0}, url={https://www.aiche.org/conferences/aiche-annual-meeting/2018/proceeding/paper/6kc-soft-stretchable-wearable-platforms-sensing-and-energy-harvesting-applications}, author={Bandodkar, Amay J. and Wang, Joseph and Rogers, John A.}, year={2018} }
 @article{kim_zhang_won_bandodkar_sekine_xue_koo_harshman_martin_park_et al._2018, title={Super-Absorbent Polymer Valves and Colorimetric Chemistries for Time-Sequenced Discrete Sampling and Chloride Analysis of Sweat via Skin-Mounted Soft Microfluidics}, volume={14}, ISSN={1613-6810}, url={http://dx.doi.org/10.1002/smll.201703334}, DOI={10.1002/smll.201703334}, abstractNote={Abstract}, number={12}, journal={Small}, publisher={Wiley}, author={Kim, Sung Bong and Zhang, Yi and Won, Sang Min and Bandodkar, Amay J. and Sekine, Yurina and Xue, Yeguang and Koo, Jahyun and Harshman, Sean W. and Martin, Jennifer A. and Park, Jeong Min and et al.}, year={2018}, month={Feb}, pages={1703334} }
 @book{wang_windmiller_bandodkar_2018, title={Wearable electrochemical sensors}, number={20180220967A1}, author={Wang, Joseph and Windmiller, Joshua Ray and Bandodkar, Amay Jairaj}, year={2018} }
 @article{abellán-llobregat_jeerapan_bandodkar_vidal_canals_wang_morallón_2017, title={A stretchable and screen-printed electrochemical sensor for glucose determination in human perspiration}, volume={91}, ISSN={0956-5663}, url={http://dx.doi.org/10.1016/j.bios.2017.01.058}, DOI={10.1016/j.bios.2017.01.058}, abstractNote={Here we present two types of all-printable, highly stretchable, and inexpensive devices based on platinum (Pt)-decorated graphite for glucose determination in physiological fluids. Said devices are: a non-enzymatic sensor and an enzymatic biosensor, the latter showing promising results. Glucose has been quantified by measuring hydrogen peroxide (H2O2) reduction by chronoamperometry at −0.35 V (vs pseudo-Ag/AgCl) using glucose oxidase immobilized on Pt-decorated graphite. The sensor performs well for the quantification of glucose in phosphate buffer solution (0.25 M PBS, pH 7.0), with a linear range between 0 mM and 0.9 mM, high sensitivity and selectivity, and a low limit of detection (LOD). Thus, it provides an alternative non-invasive and on-body quantification of glucose levels in human perspiration. This biosensor has been successfully applied on real human perspiration samples and results also show a significant correlation between glucose concentration in perspiration and glucose concentration in blood measured by a commercial glucose meter.}, journal={Biosensors and Bioelectronics}, publisher={Elsevier BV}, author={Abellán-Llobregat, A. and Jeerapan, Itthipon and Bandodkar, A. and Vidal, L. and Canals, A. and Wang, J. and Morallón, E.}, year={2017}, month={May}, pages={885–891} }
 @article{mohan_kim_gu_bandodkar_you_kumar_kurniawan_xu_wang_2017, title={Merging of Thin- and Thick-Film Fabrication Technologies: Toward Soft Stretchable “Island-Bridge” Devices}, volume={2}, ISSN={2365-709X}, url={http://dx.doi.org/10.1002/admt.201600284}, DOI={10.1002/admt.201600284}, abstractNote={DOI: 10.1002/admt.201600284 fabrication of such materials onto deterministically stretchable designs thus requires reliance on other fabrication techniques. The key focus of the present work was to develop a strategy for combining lithography (thin-film) and screen-printing (thick-film) techniques to realize deterministic, high-performance stretchable devices. Screen printing has been widely used toward large-scale, cost-effective incorporation of a myriad of materials onto numerous substrates for various applications.[19,20] However, most of the printable inks form either rigid or flexible films. Developing stretch-enduring inks is challenging as only a handful of elastomeric binders and functional materials can be homogeneously dispersed to achieve highperformance stretchable inks. While lithographic and printing techniques have been the primary methods used for fabricating wearable devices, their distinct and complementary advantages and characteristics have not been combined. The described new hybrid fabrication process, combining the printing of functional ink materials onto lithographically stretchable deterministic patterns, represents an attractive route that can address the challenges of each individual technique. For example, while lithography has been exploited for realizing complex stretchable systems, they are limited to thin films (<10 μm), which are not suitable for devices requiring high loading of active materials (e.g., energy harvesting and storage devices). In addition, there are limited choices of materials that can be vacuum deposited and solution etched. On the other hand, screen printing enables sufficient loading of a variety of active materials into thick (20–50 μm) films, but it suffers from meeting required layout resolutions and performance. In the hybrid system, the thick film resides over rigid isolated islands interconnected with free-standing stretchable serpentine bridges. The device can thus afford to include a wide range of rigid and lithographically incompatible materials without concern of device failure, since most of the strain is accommodated by the serpentine structures while leaving the thick-film islands unharmed. The hybrid system thus combines the best of two worlds. The hybrid pattern has been realized by first lithographically fabricating the entire “island–bridge” layout of the device in gold onto an elastomeric substrate, followed by printing the ink layer on the islands (Figure 1A). Briefly, a polyimide-coated copper film was bonded to a polydimethylsiloxane-covered glass slide. Thereafter, copper electrodes were patterned via standard lithographic technique. Subsequently, gold electrodes were patterned onto the copper design. Later, a top layer of polyimide was patterned to define the active electrode area and finally transferred to an EcoFlex layer. Subsequently, the device was transferred to the printer where electrodes were screen printed with inks. The detailed fabrication process is described in the Biointegrated soft electronic devices are expected to play crucial roles in consumer electronics,[1] healthcare,[2] and energy[3] domains to significantly transform our lifestyle. However, mating of conventional rigid electronic devices with soft biological tissues leads to significant compromise in performance.[4] The rapidly emerging field of soft, stretchable electronics has the potential to address this issue by ensuring conformal contact between wearable devices and the human body.[5] Researchers have mainly focused on using two approaches for realizing stretchable devices: deterministic[6] and random[7] composites. The deterministic composite route, also known as the “island–bridge” approach, involves lithographic fabrication of the device components onto rigid islands connected by serpentine bridges and ultimately bonding the device to a soft, stretchable elastomeric substrate.[8] When subjected to external strain, the underlying elastomeric substrate and the serpentine structures accommodate most of the stress, thus leaving the crucial device components unharmed.[5,9] On the other hand, random composite-based stretchability relies on the random incorporation of functional material within or on the elastomeric matrix to develop stretchable systems.[10] Deterministically stretchable devices have an edge over their random composite counterparts since the performance of random composite devices diminishes by incorporating the functional components within/on elastomeric substrates.[11] In contrast, deterministic systems allow fabrication of complex, stretchable devices with performance similar to conventional rigid devices.[12] Additionally, lithographically fabricated deterministic stretchable systems can possess features with a few micrometer and even sub-micrometer dimensions, thus leading to compact, multifunctional devices. However, widespread applications of such devices are hindered since there are several materials that are incompatible with the lithographic fabrication route. For example, many devices rely on nanomaterials,[13] polymer composites,[14] carbonaceous,[15] biological,[16] lowtemperature,[17] and solvent-sensitive[18] materials. Integrating these materials in microstructured forms on elastomeric substrates, for intimate contact with biological tissues, will open up new paradigms for wearable devices. High-precision scalable www.advmattechnol.de}, number={4}, journal={Advanced Materials Technologies}, publisher={Wiley}, author={Mohan, A. M. Vinu and Kim, NamHeon and Gu, Yue and Bandodkar, Amay J. and You, Jung-Min and Kumar, Rajan and Kurniawan, Jonas F. and Xu, Sheng and Wang, Joseph}, year={2017}, month={Feb}, pages={1600284} }
 @book{wang_bandodkar_mercier_2017, title={Non-invasive and wearable chemical sensors and biosensors}, number={10722160B2}, author={Wang, Joseph and Bandodkar, Amay Jairaj and Mercier, Patrick}, year={2017} }
 @article{choi_xue_xia_ray_reeder_bandodkar_kang_xu_huang_rogers_2017, title={Soft, skin-mounted microfluidic systems for measuring secretory fluidic pressures generated at the surface of the skin by eccrine sweat glands}, volume={17}, ISSN={1473-0197 1473-0189}, url={http://dx.doi.org/10.1039/c7lc00525c}, DOI={10.1039/c7lc00525c}, abstractNote={We introduce a skin-mounted microfluidic device for measuring the secretory pressure of sweat glands at the surface of the skin.}, number={15}, journal={Lab on a Chip}, publisher={Royal Society of Chemistry (RSC)}, author={Choi, Jungil and Xue, Yeguang and Xia, Wei and Ray, Tyler R. and Reeder, Jonathan T. and Bandodkar, Amay J. and Kang, Daeshik and Xu, Shuai and Huang, Yonggang and Rogers, John A.}, year={2017}, pages={2572–2580} }
 @article{bandodkar_you_kim_gu_kumar_mohan_kurniawan_imani_nakagawa_parish_et al._2017, title={Soft, stretchable, high power density electronic skin-based biofuel cells for scavenging energy from human sweat}, volume={10}, ISSN={1754-5692 1754-5706}, url={http://dx.doi.org/10.1039/c7ee00865a}, DOI={10.1039/c7ee00865a}, abstractNote={A soft, stretchable wearable biofuel cell producing ∼1 mW power from sweat is presented.}, number={7}, journal={Energy & Environmental Science}, publisher={Royal Society of Chemistry (RSC)}, author={Bandodkar, Amay J. and You, Jung-Min and Kim, Nam-Heon and Gu, Yue and Kumar, Rajan and Mohan, A. M. Vinu and Kurniawan, Jonas and Imani, Somayeh and Nakagawa, Tatsuo and Parish, Brianna and et al.}, year={2017}, pages={1581–1589} }
 @book{wang_windmiller_bandodkar_2017, title={Wearable electrochemical sensors}, number={9820692B2}, author={Wang, Joseph and Windmiller, Joshua Ray and Bandodkar, Amay Jairaj}, year={2017} }
 @article{imani_bandodkar_mohan_kumar_yu_wang_mercier_2016, title={A wearable chemical–electrophysiological hybrid biosensing system for real-time health and fitness monitoring}, volume={7}, ISSN={2041-1723}, url={http://dx.doi.org/10.1038/ncomms11650}, DOI={10.1038/ncomms11650}, abstractNote={Abstract}, number={1}, journal={Nature Communications}, publisher={Springer Science and Business Media LLC}, author={Imani, Somayeh and Bandodkar, Amay J. and Mohan, A. M. Vinu and Kumar, Rajan and Yu, Shengfei and Wang, Joseph and Mercier, Patrick P.}, year={2016}, month={May} }
 @article{kim_kumar_bandodkar_wang_2016, title={Advanced Materials for Printed Wearable Electrochemical Devices: A Review}, volume={3}, ISSN={2199-160X}, url={http://dx.doi.org/10.1002/aelm.201600260}, DOI={10.1002/aelm.201600260}, abstractNote={The field of printed wearable electronics has witnessed spectacular growth due to its promise to offer low‐cost, high‐performance devices for a broad range of applications. Among the sub‐fields of printed wearable electronics, printed wearable electrochemical systems are of special importance due to their widespread applications in healthcare, energy and security fields. These systems have opened up new avenues for body‐integrated electronics that were earlier impossible to achieve. These include wearable energy systems and sensors for a wide variety of applications. Much of the success of printed wearable electrochemical systems can be attributed to innovations in materials engineering that have led to novel inks comprising of new nanomaterials, polymers and composites. New generation of printed electrochemical devices include soft, stretchable and anatomically‐compliant devices that enable efficient bio‐integration and withstand high tensile stress associated with on‐body applications. Progress in materials science has also led to the development of self‐healing printed electrochemical systems for wearable applications. This review provides an overview of the key material requirements for ink formulations for realizing efficient wearable electrochemical systems such as batteries, supercapacitors, biofuel cells and sensors. Finally, major challenges impeding the field of wearable electrochemical systems are discussed along with future prospects of this exciting field.}, number={1}, journal={Advanced Electronic Materials}, publisher={Wiley}, author={Kim, Jayoung and Kumar, Rajan and Bandodkar, Amay J. and Wang, Joseph}, year={2016}, month={Dec}, pages={1600260} }
 @article{bandodkar_lópez_vinu mohan_yin_kumar_wang_2016, title={All-printed magnetically self-healing electrochemical devices}, volume={2}, ISSN={2375-2548}, url={http://dx.doi.org/10.1126/sciadv.1601465}, DOI={10.1126/sciadv.1601465}, abstractNote={Researchers develop self-healing inks for realizing printed electronics that can instantly recover millimeter-sized cracks.}, number={11}, journal={Science Advances}, publisher={American Association for the Advancement of Science (AAAS)}, author={Bandodkar, Amay J. and López, Cristian S. and Vinu Mohan, Allibai Mohanan and Yin, Lu and Kumar, Rajan and Wang, Joseph}, year={2016}, month={Nov}, pages={e1601465} }
 @inproceedings{bandodkar_wang_2016, title={All-printed wearable electrochemical sensors and biofuel cells}, volume={251}, booktitle={Abstracts of Papers of the American Chemical Society}, author={Bandodkar, Amay and Wang, Joseph}, year={2016} }
 @article{kim_jeerapan_imani_cho_bandodkar_cinti_mercier_wang_2016, title={Noninvasive Alcohol Monitoring Using a Wearable Tattoo-Based Iontophoretic-Biosensing System}, volume={1}, ISSN={2379-3694 2379-3694}, url={http://dx.doi.org/10.1021/acssensors.6b00356}, DOI={10.1021/acssensors.6b00356}, abstractNote={In this paper we demonstrate a wearable tattoo-based alcohol biosensing system for noninvasive alcohol monitoring in induced sweat. The skin-worn alcohol monitoring platform integrates an iontophoretic-biosensing temporary tattoo system along with flexible wireless electronics. The wearable prototype enables the transdermal delivery of the pilocarpine drug to induce sweat via iontophoresis and amperometric detection of ethanol in the generated sweat using the alcohol-oxidase enzyme and the Prussian Blue electrode transducer. The new skin-compliant biosensor displays a highly selective and sensitive response to ethanol. On-body results with human subjects show distinct differences in the current response before and after alcohol consumption, reflecting the increase of ethanol levels. The skin-worn alcohol sensor is coupled with a flexible electronics board, which controls the iontophoresis/amperometry operation and transmits data wirelessly in real time via Bluetooth communication. The new wireless epiderm...}, number={8}, journal={ACS Sensors}, publisher={American Chemical Society (ACS)}, author={Kim, Jayoung and Jeerapan, Itthipon and Imani, Somayeh and Cho, Thomas N. and Bandodkar, Amay and Cinti, Stefano and Mercier, Patrick P. and Wang, Joseph}, year={2016}, month={Jul}, pages={1011–1019} }
 @article{novel materials-based stretchable and self-healing electrochemical
                        sensors for wearable applications_2016, ISSN={2151-2043}, url={http://dx.doi.org/10.1149/ma2016-01/40/2011}, DOI={10.1149/ma2016-01/40/2011}, abstractNote={Printed electronics has acquired tremendous attention recently and its market size is expected to reach $300 billion over the next two decades. Printed electrochemical sensors, in particular, are an important sub-section of printed electronics that play a pivotal role in healthcare, energy and security domains. However, the fragile nature of these printed electrochemical devices greatly hampers the complete harnessing of their potential in many scenarios, such as, wearable applications, where harsh mechanical deformations are fairly common. External stress induced device failure is indeed the “Achilles heel” of the printed electronics field and yet not much has been done to develop printed devices that can withstand extreme stress and self-heal upon damage. We have thus attempted to fill this scientific vacuum by fabricating the first examples of all-printed, inexpensive, highly stretchable and self-healing electrochemical sensors. These novel devices have been realized by judiciously synthesizing screen printable inks that contain elastomeric binders and microcapsules loaded with self-healing agent. }, journal={ECS Meeting Abstracts}, publisher={The Electrochemical Society}, year={2016} }
 @phdthesis{bandodkar_2016, title={Printed Wearable Electrochemical Sensors for Healthcare Monitoring}, url={https://escholarship.org/uc/item/3nf886hp}, school={University of California, San Diego}, author={Bandodkar, Amay Jairaj}, year={2016} }
 @article{bandodkar_2016, title={Review—Wearable Biofuel Cells: Past, Present and Future}, volume={164}, ISSN={0013-4651 1945-7111}, url={http://dx.doi.org/10.1149/2.0031703jes}, DOI={10.1149/2.0031703jes}, abstractNote={The perspective article provides a detailed description of the major developments in the field of wearable biofuel cells. The article expounds several attributes of this newly emerging technology and its potential to address the energy needs of wearable devices. In addition to discussing important milestones reached in this field, the article also highlights the grand challenges that are presently hindering further development of wearable biofuel cells. Particular emphasis has been devoted to major issues related to biofuel cell stability, need for generating stable, high levels of power, mechanical compliance and resiliency and device aesthetics. In addition to this, the article also offers multiple pathways to address these issues. The article aims at generating interest among researchers with diverse expertise to come together on a common platform to overcome the major challenges faced by the field of wearable biofuel cells. Such collaborative efforts will be essential for the success of wearable biofuel cells and to harness their full potential. © The}, number={3}, journal={Journal of The Electrochemical Society}, publisher={The Electrochemical Society}, author={Bandodkar, Amay J.}, year={2016}, month={Nov}, pages={H3007–H3014} }
 @article{bandodkar_wang_2016, title={Wearable Biofuel Cells: A Review}, volume={28}, ISSN={1040-0397}, url={http://dx.doi.org/10.1002/elan.201600019}, DOI={10.1002/elan.201600019}, abstractNote={Abstract}, number={6}, journal={Electroanalysis}, publisher={Wiley}, author={Bandodkar, Amay J. and Wang, Joseph}, year={2016}, month={Feb}, pages={1188–1200} }
 @article{bandodkar_jeerapan_wang_2016, title={Wearable Chemical Sensors: Present Challenges and Future Prospects}, volume={1}, ISSN={2379-3694 2379-3694}, url={http://dx.doi.org/10.1021/acssensors.6b00250}, DOI={10.1021/acssensors.6b00250}, abstractNote={Wearable sensors have received considerable interest over the past decade owing to their tremendous promise for monitoring the wearers’ health, fitness, and their surroundings. However, only limited attention has been directed at developing wearable chemical sensors that offer more comprehensive information about a wearer’s well-being. The development of wearable chemical sensors faces multiple challenges on various fronts. This perspective reviews key challenges and technological gaps impeding the successful realization of effective wearable chemical sensor systems, related to materials, power, analytical procedure, communication, data acquisition, processing, and security. Size, rigidity, and operational requirements of present chemical sensors are incompatible with wearable technology. Sensor stability and on-body sensor surface regeneration constitute key analytical challenges. Similarly, present wearable power sources are incapable of meeting the requirements for wearable electronics owing to their l...}, number={5}, journal={ACS Sensors}, publisher={American Chemical Society (ACS)}, author={Bandodkar, Amay J. and Jeerapan, Itthipon and Wang, Joseph}, year={2016}, month={May}, pages={464–482} }
 @inproceedings{imani_mercier_bandodkar_kim_wang_2016, title={Wearable chemical sensors: Opportunities and challenges}, volume={2016-July}, ISBN={9781479953417}, url={http://dx.doi.org/10.1109/iscas.2016.7527442}, DOI={10.1109/iscas.2016.7527442}, abstractNote={Wearable systems show considerable promise in monitoring and assessing the real-time performance of athletes, the health status of patients, or the general well-being of interested users. Most wearables today focus on monitoring physical parameters (e.g., activity, respiration rate, etc.), or electrophysiology (e.g., ECG, EEG, etc.). In order to augment the richness of collected data, the next-generation of wearables will also be capable of monitoring underlying chemical homeostatis of the user, for example through measurement of glucose in interstitial fluid, lactate in saliva, or electrolytes in sweat. This paper discusses the challenges of building wearable chemical biosensors, including biosensor functionalization, flexible material engineering, bioelectronic integration, and data analytics.}, booktitle={2016 IEEE International Symposium on Circuits and Systems (ISCAS)}, publisher={IEEE}, author={Imani, Somayeh and Mercier, Patrick P. and Bandodkar, Amay J. and Kim, Jayoung and Wang, Joseph}, year={2016}, month={May}, pages={1122–1125} }
 @article{bandodkar_nuñez‐flores_jia_wang_2015, title={All‐Printed Stretchable Electrochemical Devices}, volume={27}, ISSN={0935-9648 1521-4095}, url={http://dx.doi.org/10.1002/adma.201500768}, DOI={10.1002/adma.201500768}, abstractNote={The fabrication and characterization of all-printed, inexpensive, stretchable electrochemical devices is described. These devices are based on specially engineered inks that can withstand severe tensile strain, as high as 100%, without any significant effect on their electrochemical properties. Such stretchable electrochemical devices should be attractive for diverse sensing and energy applications.}, number={19}, journal={Advanced Materials}, publisher={Wiley}, author={Bandodkar, Amay J. and Nuñez‐Flores, Rogelio and Jia, Wenzhao and Wang, Joseph}, year={2015}, month={Apr}, pages={3060–3065} }
 @article{bandodkar_jia_ramírez_wang_2015, title={Biocompatible Enzymatic Roller Pens for Direct Writing of Biocatalytic Materials: “Do-it-Yourself” Electrochemical Biosensors}, volume={4}, ISSN={2192-2640}, url={http://dx.doi.org/10.1002/adhm.201400808}, DOI={10.1002/adhm.201400808}, abstractNote={The development of enzymatic‐ink‐based roller pens for direct drawing of biocatalytic sensors, in general, and for realizing renewable glucose sensor strips, in particular, is described. The resulting enzymatic‐ink pen allows facile fabrication of high‐quality inexpensive electrochemical biosensors of any design by the user on a wide variety of surfaces having complex textures with minimal user training. Unlike prefabricated sensors, this approach empowers the end user with the ability of “on‐demand” and “on‐site” designing and fabricating of biocatalytic sensors to suit their specific requirement. The resulting devices are thus referred to as “do‐it‐yourself” sensors. The bio­active pens produce highly reproducible biocatalytic traces with minimal edge roughness. The composition of the new enzymatic inks has been optimized for ensuring good biocatalytic activity, electrical conductivity, biocompati­bility, reproducible writing, and surface adherence. The resulting inks are characterized using spectroscopic, viscometric, electrochemical, thermal and microscopic techniques. Applicability to renewable blood glucose testing, epidermal glucose monitoring, and on‐leaf phenol detection are demonstrated in connection to glucose oxidase and tyrosinase‐based carbon inks. The “do‐it‐yourself” renewable glucose sensor strips offer a “fresh,” reproducible, low‐cost biocatalytic sensor surface for each blood test. The ability to directly draw biocatalytic conducting traces even on unconventional surfaces opens up new avenues in various sensing applications in low‐resource settings and holds great promise for diverse healthcare, environmental, and defense domains.}, number={8}, journal={Advanced Healthcare Materials}, publisher={Wiley}, author={Bandodkar, Amay J. and Jia, Wenzhao and Ramírez, Julian and Wang, Joseph}, year={2015}, month={Feb}, pages={1215–1224} }
 @article{bandodkar_jeerapan_you_nuñez-flores_wang_2015, title={Highly Stretchable Fully-Printed CNT-Based Electrochemical Sensors and Biofuel Cells: Combining Intrinsic and Design-Induced Stretchability}, volume={16}, ISSN={1530-6984 1530-6992}, url={http://dx.doi.org/10.1021/acs.nanolett.5b04549}, DOI={10.1021/acs.nanolett.5b04549}, abstractNote={We present the first example of an all-printed, inexpensive, highly stretchable CNT-based electrochemical sensor and biofuel cell array. The synergistic effect of utilizing specially tailored screen printable stretchable inks that combine the attractive electrical and mechanical properties of CNTs with the elastomeric properties of polyurethane as a binder along with a judiciously designed free-standing serpentine pattern enables the printed device to possess two degrees of stretchability. Owing to these synergistic design and nanomaterial-based ink effects, the device withstands extremely large levels of strains (up to 500% strain) with negligible effect on its structural integrity and performance. This represents the highest stretchability offered by a printed device reported to date. Extensive electrochemical characterization of the printed device reveal that repeated stretching, torsional twisting, and indenting stress has negligible impact on its electrochemical properties. The wide-range applicability of this platform to realize highly stretchable CNT-based electrochemical sensors and biofuel cells has been demonstrated by fabricating and characterizing potentiometric ammonium sensor, amperometric enzyme-based glucose sensor, enzymatic glucose biofuel cell, and self-powered biosensor. Highly stretchable printable multianalyte sensor, multifuel biofuel cell, or any combination thereof can thus be realized using the printed CNT array. Such combination of intrinsically stretchable printed nanomaterial-based electrodes and strain-enduring design patterns holds considerable promise for creating an attractive class of inexpensive multifunctional, highly stretchable printed devices that satisfy the requirements of diverse healthcare and energy fields wherein resilience toward extreme mechanical deformations is mandatory.}, number={1}, journal={Nano Letters}, publisher={American Chemical Society (ACS)}, author={Bandodkar, Amay J. and Jeerapan, Itthipon and You, Jung-Min and Nuñez-Flores, Rogelio and Wang, Joseph}, year={2015}, month={Dec}, pages={721–727} }
 @article{bandodkar_mohan_lópez_ramírez_wang_2015, title={Self-Healing Inks for Autonomous Repair of Printable Electrochemical Devices}, volume={1}, ISSN={2199-160X}, url={http://dx.doi.org/10.1002/aelm.201500289}, DOI={10.1002/aelm.201500289}, abstractNote={DOI: 10.1002/aelm.201500289 leads to permanent failure. Therefore, it is critical to develop self-healing conductive inks for fabricating intelligent all-printed electrochemical devices that autonomously restore the lost electrical conductivity caused by mechanical damage, degradation, and failure. In the present work we report, for the fi rst time, the synthesis of printable inks containing self-healing microcapsules for fabricating self-repairable inexpensive electrochemical devices. Unlike previous work, [ 18,20 ] the new tailor-made conductive inks contain the self-healing capsules and do not require a separate coating of the microcapsules over the printed structure. By judiciously identifying the binder and thinner, we were able to synthesize conductive inks that could be easily loaded with the healing capsules while enabling convenient printing ( Figure 1 A). When the printed device is damaged, the capsules release the hexyl-acetate healing solvent to restore the mechanical and electrical contacts. Since the capsules are loaded directly in the inks, the entire footprint of the printed electrochemical devices has the ability to self-heal upon mechanical damage. By leveraging printing technology and the self-healing inks, we demonstrate smart electrochemical devices that rapidly self-repair mechanical damage at ambient temperature, and restore electrochemical performance. A typical screen-printed conductive ink is composed of the conductor particles, polymeric binder, and other additives. [ 37 ]}, number={12}, journal={Advanced Electronic Materials}, publisher={Wiley}, author={Bandodkar, Amay J. and Mohan, Vinu and López, Cristian S. and Ramírez, Julian and Wang, Joseph}, year={2015}, month={Nov}, pages={1500289} }
 @article{bandodkar_jia_wang_2015, title={Tattoo-Based Wearable Electrochemical Devices: A Review}, volume={27}, ISSN={1040-0397}, url={http://dx.doi.org/10.1002/elan.201400537}, DOI={10.1002/elan.201400537}, abstractNote={Abstract}, number={3}, journal={Electroanalysis}, publisher={Wiley}, author={Bandodkar, Amay J. and Jia, Wenzhao and Wang, Joseph}, year={2015}, month={Jan}, pages={562–572} }
 @article{kim_de araujo_samek_bandodkar_jia_brunetti_paixão_wang_2015, title={Wearable temporary tattoo sensor for real-time trace metal monitoring in human sweat}, volume={51}, ISSN={1388-2481}, url={http://dx.doi.org/10.1016/j.elecom.2014.11.024}, DOI={10.1016/j.elecom.2014.11.024}, abstractNote={A wearable electrochemical sensor for non-invasive monitoring of trace metals in human perspiration is described. The temporary tattoo-based printable stripping-voltammetric sensor has been applied for real-time monitoring of zinc in sweat using a bismuth/Nafion film electrode during physical activity. The Zn temporary tattoo sensor withstands repeated mechanical stress and displays a well-defined Zn response during on-body testing. Such a non-invasive stripping-voltammetric detection could be readily expanded to epidermal measurements of other relevant heavy metals.}, journal={Electrochemistry Communications}, publisher={Elsevier BV}, author={Kim, Jayoung and de Araujo, William R. and Samek, Izabela A. and Bandodkar, Amay J. and Jia, Wenzhao and Brunetti, Barbara and Paixão, Thiago R.L.C. and Wang, Joseph}, year={2015}, month={Feb}, pages={41–45} }
 @article{berchmans_bandodkar_jia_ramírez_meng_wang_2014, title={An epidermal alkaline rechargeable Ag–Zn printable tattoo battery for wearable electronics}, volume={2}, ISSN={2050-7488 2050-7496}, url={http://dx.doi.org/10.1039/c4ta03256j}, DOI={10.1039/c4ta03256j}, abstractNote={A body-compliant epidermal rechargeable Ag–Zn printable tattoo battery is reported.}, number={38}, journal={J. Mater. Chem. A}, publisher={Royal Society of Chemistry (RSC)}, author={Berchmans, Sheela and Bandodkar, Amay J. and Jia, Wenzhao and Ramírez, Julian and Meng, Ying S. and Wang, Joseph}, year={2014}, pages={15788–15795} }
 @article{bandodkar_molinnus_mirza_guinovart_windmiller_valdés-ramírez_andrade_schöning_wang_2014, title={Epidermal tattoo potentiometric sodium sensors with wireless signal transduction for continuous non-invasive sweat monitoring}, volume={54}, ISSN={0956-5663}, url={http://dx.doi.org/10.1016/j.bios.2013.11.039}, DOI={10.1016/j.bios.2013.11.039}, abstractNote={This article describes the fabrication, characterization and application of an epidermal temporary-transfer tattoo-based potentiometric sensor, coupled with a miniaturized wearable wireless transceiver, for real-time monitoring of sodium in the human perspiration. Sodium excreted during perspiration is an excellent marker for electrolyte imbalance and provides valuable information regarding an individual's physical and mental wellbeing. The realization of the new skin-worn non-invasive tattoo-like sensing device has been realized by amalgamating several state-of-the-art thick film, laser printing, solid-state potentiometry, fluidics and wireless technologies. The resulting tattoo-based potentiometric sodium sensor displays a rapid near-Nernstian response with negligible carryover effects, and good resiliency against various mechanical deformations experienced by the human epidermis. On-body testing of the tattoo sensor coupled to a wireless transceiver during exercise activity demonstrated its ability to continuously monitor sweat sodium dynamics. The real-time sweat sodium concentration was transmitted wirelessly via a body-worn transceiver from the sodium tattoo sensor to a notebook while the subjects perspired on a stationary cycle. The favorable analytical performance along with the wearable nature of the wireless transceiver makes the new epidermal potentiometric sensing system attractive for continuous monitoring the sodium dynamics in human perspiration during diverse activities relevant to the healthcare, fitness, military, healthcare and skin-care domains.}, journal={Biosensors and Bioelectronics}, publisher={Elsevier BV}, author={Bandodkar, Amay J. and Molinnus, Denise and Mirza, Omar and Guinovart, Tomás and Windmiller, Joshua R. and Valdés-Ramírez, Gabriela and Andrade, Francisco J. and Schöning, Michael J. and Wang, Joseph}, year={2014}, month={Apr}, pages={603–609} }
 @article{valdés-ramírez_li_kim_jia_bandodkar_nuñez-flores_miller_wu_narayan_windmiller_et al._2014, title={Microneedle-based self-powered glucose sensor}, volume={47}, ISSN={1388-2481}, url={http://dx.doi.org/10.1016/j.elecom.2014.07.014}, DOI={10.1016/j.elecom.2014.07.014}, abstractNote={A microneedle-based self-powered biofuel-cell glucose sensor is described. The biofuel cell sensor makes use of the integration of modified carbon pastes into hollow microneedle devices. The system displays defined dependence of the power density vs glucose concentration in artificial interstitialfluid. An excellent selectivity against common electroactive interferences and long-term stability are obtained. The attractive performance of the device indicates considerable promise for subdermal glucose monitoring.}, journal={Electrochemistry Communications}, publisher={Elsevier BV}, author={Valdés-Ramírez, Gabriela and Li, Ya-Chieh and Kim, Jayoung and Jia, Wenzhao and Bandodkar, Amay J. and Nuñez-Flores, Rogelio and Miller, Philip R. and Wu, Shu-Yii and Narayan, Roger and Windmiller, Joshua R. and et al.}, year={2014}, month={Oct}, pages={58–62} }
 @article{kim_valdés-ramírez_bandodkar_jia_martinez_ramírez_mercier_wang_2014, title={Non-invasive mouthguard biosensor for continuous salivary monitoring of metabolites}, volume={139}, ISSN={0003-2654 1364-5528}, url={http://dx.doi.org/10.1039/c3an02359a}, DOI={10.1039/c3an02359a}, abstractNote={A wearable mouthguard electrochemical biosensor for salivary metabolites is described. Such non-invasive mouthguard metabolite biosensors provide real-time information regarding a wearer's health, performance and stress level, and thus hold considerable promise for diverse biomedical and fitness applications.}, number={7}, journal={The Analyst}, publisher={Royal Society of Chemistry (RSC)}, author={Kim, Jayoung and Valdés-Ramírez, Gabriela and Bandodkar, Amay J. and Jia, Wenzhao and Martinez, Alexandra G. and Ramírez, Julian and Mercier, Patrick and Wang, Joseph}, year={2014}, pages={1632–1636} }
 @article{bandodkar_wang_2014, title={Non-invasive wearable electrochemical sensors: a review}, volume={32}, ISSN={0167-7799}, url={http://dx.doi.org/10.1016/j.tibtech.2014.04.005}, DOI={10.1016/j.tibtech.2014.04.005}, abstractNote={Wearable sensors have garnered considerable recent interest owing to their tremendous promise for a plethora of applications. Yet the absence of reliable non-invasive chemical sensors has greatly hindered progress in the area of on-body sensing. Electrochemical sensors offer considerable promise as wearable chemical sensors that are suitable for diverse applications owing to their high performance, inherent miniaturization, and low cost. A wide range of wearable electrochemical sensors and biosensors has been developed for real-time non-invasive monitoring of electrolytes and metabolites in sweat, tears, or saliva as indicators of a wearer's health status. With continued innovation and attention to key challenges, such non-invasive electrochemical sensors and biosensors are expected to open up new exciting avenues in the field of wearable wireless sensing devices and body-sensor networks, and thus find considerable use in a wide range of personal health-care monitoring applications, as well as in sport and military applications.}, number={7}, journal={Trends in Biotechnology}, publisher={Elsevier BV}, author={Bandodkar, Amay J. and Wang, Joseph}, year={2014}, month={Jul}, pages={363–371} }
 @article{bandodkar_jia_yardımcı_wang_ramirez_wang_2014, title={Tattoo-Based Noninvasive Glucose Monitoring: A Proof-of-Concept Study}, volume={87}, ISSN={0003-2700 1520-6882}, url={http://dx.doi.org/10.1021/ac504300n}, DOI={10.1021/ac504300n}, abstractNote={We present a proof-of-concept demonstration of an all-printed temporary tattoo-based glucose sensor for noninvasive glycemic monitoring. The sensor represents the first example of an easy-to-wear flexible tattoo-based epidermal diagnostic device combining reverse iontophoretic extraction of interstitial glucose and an enzyme-based amperometric biosensor. In-vitro studies reveal the tattoo sensor's linear response toward physiologically relevant glucose levels with negligible interferences from common coexisting electroactive species. The iontophoretic-biosensing tattoo platform is reduced to practice by applying the device on human subjects and monitoring variations in glycemic levels due to food consumption. Correlation of the sensor response with that of a commercial glucose meter underscores the promise of the tattoo sensor to detect glucose levels in a noninvasive fashion. Control on-body experiments demonstrate the importance of the reverse iontophoresis operation and validate the sensor specificity. This preliminary investigation indicates that the tattoo-based iontophoresis-sensor platform holds considerable promise for efficient diabetes management and can be extended toward noninvasive monitoring of other physiologically relevant analytes present in the interstitial fluid.}, number={1}, journal={Analytical Chemistry}, publisher={American Chemical Society (ACS)}, author={Bandodkar, Amay J. and Jia, Wenzhao and Yardımcı, Ceren and Wang, Xuan and Ramirez, Julian and Wang, Joseph}, year={2014}, month={Dec}, pages={394–398} }
 @article{jia_wang_imani_bandodkar_ramírez_mercier_wang_2014, title={Wearable textile biofuel cells for powering electronics}, volume={2}, ISSN={2050-7488 2050-7496}, url={http://dx.doi.org/10.1039/c4ta04796f}, DOI={10.1039/c4ta04796f}, abstractNote={The article reports on the fabrication of wearable textile biofuel cells integrated with energy storage device for powering electronics with wearer’s perspiration as a fuel source.}, number={43}, journal={J. Mater. Chem. A}, publisher={Royal Society of Chemistry (RSC)}, author={Jia, Wenzhao and Wang, Xuan and Imani, Somayeh and Bandodkar, Amay J. and Ramírez, Julian and Mercier, Patrick P. and Wang, Joseph}, year={2014}, pages={18184–18189} }
 @article{guinovart_bandodkar_windmiller_andrade_wang_2013, title={A potentiometric tattoo sensor for monitoring ammonium in sweat}, volume={138}, ISSN={0003-2654 1364-5528}, url={http://dx.doi.org/10.1039/c3an01672b}, DOI={10.1039/c3an01672b}, abstractNote={The development and analytical characterization of a novel ion-selective potentiometric cell in a temporary-transfer tattoo platform for monitoring ammonium levels in sweat is presented. The fabrication of this skin-worn sensor, which is based on a screen-printed design, incorporates all-solid-state potentiometric sensor technology for both the working and reference electrodes, in connection to ammonium-selective polymeric membrane based on the nonactin ionophore. The resulting tattooed potentiometric sensor exhibits a working range between 10(-4) M to 0.1 M, well within the physiological levels of ammonium in sweat. Testing under stringent mechanical stress expected on the epidermis shows that the analytical performance is not affected by factors such as stretching or bending. Since the levels of ammonium are related to the breakdown of proteins, the new wearable potentiometric tattoo sensor offers considerable promise for monitoring sport performance or detecting metabolic disorders in healthcare. Such combination of the epidermal integration, screen-printed technology and potentiometric sensing represents an attractive path towards non-invasive monitoring of a variety of electrolytes in human perspiration.}, number={22}, journal={The Analyst}, publisher={Royal Society of Chemistry (RSC)}, author={Guinovart, Tomàs and Bandodkar, Amay J. and Windmiller, Joshua R. and Andrade, Francisco J. and Wang, Joseph}, year={2013}, pages={7031} }
 @article{jia_bandodkar_valdés-ramírez_windmiller_yang_ramírez_chan_wang_2013, title={Electrochemical Tattoo Biosensors for Real-Time Noninvasive Lactate Monitoring in Human Perspiration}, volume={85}, ISSN={0003-2700 1520-6882}, url={http://dx.doi.org/10.1021/ac401573r}, DOI={10.1021/ac401573r}, abstractNote={The present work describes the first example of real-time noninvasive lactate sensing in human perspiration during exercise events using a flexible printed temporary-transfer tattoo electrochemical biosensor that conforms to the wearer's skin. The new skin-worn enzymatic biosensor exhibits chemical selectivity toward lactate with linearity up to 20 mM and demonstrates resiliency against continuous mechanical deformation expected from epidermal wear. The device was applied successfully to human subjects for real-time continuous monitoring of sweat lactate dynamics during prolonged cycling exercise. The resulting temporal lactate profiles reflect changes in the production of sweat lactate upon varying the exercise intensity. Such skin-worn metabolite biosensors could lead to useful insights into physical performance and overall physiological status, hence offering considerable promise for diverse sport, military, and biomedical applications.}, number={14}, journal={Analytical Chemistry}, publisher={American Chemical Society (ACS)}, author={Jia, Wenzhao and Bandodkar, Amay J. and Valdés-Ramírez, Gabriela and Windmiller, Joshua R. and Yang, Zhanjun and Ramírez, Julian and Chan, Garrett and Wang, Joseph}, year={2013}, month={Jul}, pages={6553–6560} }
 @article{jia_valdés-ramírez_bandodkar_windmiller_wang_2013, title={Epidermal Biofuel Cells: Energy Harvesting from Human Perspiration}, volume={52}, ISSN={1433-7851}, url={http://dx.doi.org/10.1002/anie.201302922}, DOI={10.1002/anie.201302922}, abstractNote={The healthcare industry has recently experienced a major paradigm shift towards wearable biomedical devices. [1] Such devices have the ability to monitor vital physiological parameters, such as heart rate or blood pressure. [2] Particular recent attention has been directed towards skin-worn electronic devices fabricated by novel hybrid techniques for the measurement of these vital signs. [3] Despite dramatic technological advances, further progress in the arena of on-body biomedical devices has been hindered by the lack of effective wearable power sources able to scavenge sufficient energy from the wearer. Major efforts have thus been directed towards the identification of a suitable wearable power source that offers conformal integration with the wearer(cid:2)s body. This activity has resulted in the development of flexible thin-film batteries, piezoelectric nanogenerators, wearable solar cells, mircosupercapacitors, and endocochlear-potential-based bio-batteries. [4] Nevertheless, new body-worn conformal power sources able to extract biochemical energy from the wearer(cid:2)s body (and his/her epidermis, in particular) are still highly desired. Herein we demonstrate the ability to generate substantial levels of electrical power from human perspiration in a non-invasive and continuous fashion through the use of epidermal biofuel cells based on temporary transfer tattoos (tBFCs). Enzymatic BFCs}, number={28}, journal={Angewandte Chemie International Edition}, publisher={Wiley}, author={Jia, Wenzhao and Valdés-Ramírez, Gabriela and Bandodkar, Amay J. and Windmiller, Joshua R. and Wang, Joseph}, year={2013}, month={May}, pages={7233–7236} }
 @article{bandodkar_o'mahony_ramírez_samek_anderson_windmiller_wang_2013, title={Solid-state Forensic Finger sensor for integrated sampling and detection of gunshot residue and explosives: towards ‘Lab-on-a-finger’}, volume={138}, ISSN={0003-2654 1364-5528}, url={http://dx.doi.org/10.1039/c3an01179h}, DOI={10.1039/c3an01179h}, abstractNote={Increasing security needs require field-deployable, on-the-spot detection tools for the rapid and reliable identification of gunshot residue (GSR) and nitroaromatic explosive compounds. This manuscript presents a simple, all-solid-state, wearable fingertip sensor for the rapid on-site voltammetric screening of GSR and explosive surface residues. To fabricate the new Forensic Fingers, we screen-print a three-electrode setup onto a nitrile finger cot, and coat another finger cot with an ionogel electrolyte layer. The new integrated sampling/detection methodology relies on 'voltammetry of microparticles' (VMP) and involves an initial mechanical transfer of trace amounts of surface-confined analytes directly onto the fingertip-based electrode contingent. Voltammetric measurements of the sample residues are carried out upon bringing the working electrode (printed on the index finger cot) in direct contact with a second finger cot coated with an ionogel electrolyte (worn on the thumb), thus completing the solid-state electrochemical cell. Sampling and screening are performed in less than four minutes and generate distinct voltammetric fingerprints which are specific to both GSR and explosives. The use of the solid, flexible ionogel electrolyte eliminates any liquid handling which can resolve problems associated with leakage, portability and contamination. A detailed study reveals that the fingertip detection system can rapidly identify residues of GSR and nitroaromatic compounds with high specificity, without compromising its attractive behavior even after undergoing repeated mechanical stress. This new integrated sampling/detection fingertip strategy holds considerable promise as a rapid, effective and low-cost approach for on-site crime scene investigations in various forensic scenarios.}, number={18}, journal={The Analyst}, publisher={Royal Society of Chemistry (RSC)}, author={Bandodkar, Amay J. and O'Mahony, Aoife M. and Ramírez, Julian and Samek, Izabela A. and Anderson, Sean M. and Windmiller, Joshua R. and Wang, Joseph}, year={2013}, pages={5288} }
 @article{bandodkar_hung_jia_valdés-ramírez_windmiller_martinez_ramírez_chan_kerman_wang_2013, title={Tattoo-based potentiometric ion-selective sensors for epidermal pH monitoring}, volume={138}, ISSN={0003-2654 1364-5528}, url={http://dx.doi.org/10.1039/c2an36422k}, DOI={10.1039/c2an36422k}, abstractNote={This article presents the fabrication and characterization of novel tattoo-based solid-contact ion-selective electrodes (ISEs) for non-invasive potentiometric monitoring of epidermal pH levels. The new fabrication approach combines commercially available temporary transfer tattoo paper with conventional screen printing and solid-contact polymer ISE methodologies. The resulting tattoo-based potentiometric sensors exhibit rapid and sensitive response to a wide range of pH changes with no carry-over effects. Furthermore, the tattoo ISE sensors endure repetitive mechanical deformation, which is a key requirement of wearable and epidermal sensors. The flexible and conformal nature of the tattoo sensors enable them to be mounted on nearly any exposed skin surface for real-time pH monitoring of the human perspiration, as illustrated from the response during a strenuous physical activity. The resulting tattoo-based ISE sensors offer considerable promise as wearable potentiometric sensors suitable for diverse applications.}, number={1}, journal={The Analyst}, publisher={Royal Society of Chemistry (RSC)}, author={Bandodkar, Amay J. and Hung, Vinci W. S. and Jia, Wenzhao and Valdés-Ramírez, Gabriela and Windmiller, Joshua R. and Martinez, Alexandra G. and Ramírez, Julian and Chan, Garrett and Kerman, Kagan and Wang, Joseph}, year={2013}, pages={123–128} }
 @article{windmiller_bandodkar_valdés-ramírez_parkhomovsky_martinez_wang_2012, title={Electrochemical sensing based on printable temporary transfer tattoos}, volume={48}, ISSN={1359-7345 1364-548X}, url={http://dx.doi.org/10.1039/c2cc32839a}, DOI={10.1039/c2cc32839a}, abstractNote={The realization of epidermal chemical sensing requires a fabrication methodology compatible with the non-planarity and irregularities of the human anatomy. This communication describes the development of printed temporary transfer tattoo (T3) electrochemical sensors for physiological and security monitoring of chemical constituents leading to the demonstration of 'electronic skin'.}, number={54}, journal={Chemical Communications}, publisher={Royal Society of Chemistry (RSC)}, author={Windmiller, Joshua Ray and Bandodkar, Amay Jairaj and Valdés-Ramírez, Gabriela and Parkhomovsky, Serguey and Martinez, Alexandra Gabrielle and Wang, Joseph}, year={2012}, pages={6794} }
 @article{windmiller_bandodkar_parkhomovsky_wang_2012, title={Erratum: Stamp transfer electrodes for electrochemical sensing on non-planar and oversized surfaces (Analyst (2012) 137 (1570-1575) DOI:10.1039/C2AN35041F)}, volume={137}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84870492918&partnerID=MN8TOARS}, DOI={10.1039/c2an90108k}, number={24}, journal={Analyst}, author={Windmiller, J.R. and Bandodkar, A.J. and Parkhomovsky, S. and Wang, J.}, year={2012}, pages={5925} }
 @article{matharu_bandodkar_gupta_malhotra_2012, title={Fundamentals and application of ordered molecular assemblies to affinity biosensing}, volume={41}, ISSN={0306-0012 1460-4744}, url={http://dx.doi.org/10.1039/c1cs15145b}, DOI={10.1039/c1cs15145b}, abstractNote={Organization of biomolecules in two/three dimensional assemblies has recently aroused much interest in nanobiotechnology. In this context, the development of techniques for controlling spatial arrangement and orientation of the desired molecules to generate highly-ordered nanostructures in the form of a mono/multi layer is considered highly significant. The studies of monolayer films to date have focused on three distinct methods of preparation: (i) the Langmuir-Blodgett (LB) technique, involving the transfer of a monolayer assembled at the gas-liquid interface; (ii) self-assembly at the liquid-solid interface, based on spontaneous adsorption of desired molecules from a solution directly onto a solid surface; and (iii) Layer-by-layer (LBL) self-assembly at a liquid-solid interface, based on inter-layer electrostatic attractions for fabrication of multilayers. A variety of monolayers have been utilized to fabricate biomolecular electronic devices including biosensors. The composition of a monolayer based matrix has been found to influence the activity(ies) of biomolecule(s). We present comprehensive and critical analysis of ordered molecular assemblies formed by LB and self-assembly with potential applications to affinity biosensing. This critical review on fundamentals and application of ordered molecular assemblies to affinity biosensing is likely to benefit researchers working in this as well as related fields of research (401 references).}, number={3}, journal={Chem. Soc. Rev.}, publisher={Royal Society of Chemistry (RSC)}, author={Matharu, Zimple and Bandodkar, Amay Jairaj and Gupta, Vinay and Malhotra, Bansi Dhar}, year={2012}, pages={1363–1402} }
 @article{windmiller_bandodkar_parkhomovsky_wang_2012, title={Stamp transfer electrodes for electrochemical sensing on non-planar and oversized surfaces}, volume={137}, ISSN={0003-2654 1364-5528}, url={http://dx.doi.org/10.1039/c2an35041f}, DOI={10.1039/c2an35041f}, abstractNote={This article describes a new alternative approach to the fabrication of printed electrochemical sensors and biosensors based on the transfer of electrode patterns comprising common conductive and insulating inks from elastomeric stamps to a wide variety of rigid and flexible substrates. This simple, low cost, yet robust methodology is demonstrated to be well-suited for the formation of electrochemical sensors on non-planar substrates and large objects/structures, which have traditionally been off-limits to conventional screen printing techniques. Furthermore, the stamped electrode devices are shown to exhibit electrochemical performance that rivals that of their screen printed counterparts and display resilience against severe mechanical deformation. The stamp transfer approach is further extended to the demonstration of epidermal electrochemical sensors through the transfer of the electrode patterns directly onto the skin. The resulting sensors demonstrate a wide range of usability, from the detection of various physiological analytes, including uric acid on the skin, to the identification of residues originating from the handling of munitions and explosives. The migration of printable electrochemical sensors to non-conventional (non-planar and/or oversized) surfaces provides new opportunities within the personal healthcare, fitness, forensics, homeland security, and environmental monitoring domains.}, number={7}, journal={The Analyst}, publisher={Royal Society of Chemistry (RSC)}, author={Windmiller, Joshua Ray and Bandodkar, Amay Jairaj and Parkhomovsky, Serguey and Wang, Joseph}, year={2012}, pages={1570} }
 @article{o'mahony_windmiller_samek_bandodkar_wang_2012, title={“Swipe and Scan”: Integration of sampling and analysis of gunshot metal residues at screen-printed electrodes}, volume={23}, ISSN={1388-2481}, url={http://dx.doi.org/10.1016/j.elecom.2012.07.004}, DOI={10.1016/j.elecom.2012.07.004}, abstractNote={Increasing security needs require field-deployable, on-the-spot detection tools for the rapid and reliable identification of gunshot residue (GSR), and thus the collection of GSR samples is a crucial step in forensic analysis. In this work we demonstrate a novel protocol integrating GSR sampling and electroanalysis using microfabricated carbon sensor-strips. The new integrated sampling/detection methodology relies on abrasive stripping voltammetry (AbrSV) involving an initial mechanical transfer of trace amounts of surface-confined GSR from the hand of a suspect directly onto the electrode contingent of the sensor strip, which is immediately ready for electrochemical analysis. The integrated sampling/detection method holds much promise as a portable, rapid and inexpensive system to promptly identify a subject who has discharged a firearm in various forensic scenarios.}, number={1}, journal={Electrochemistry Communications}, publisher={Elsevier BV}, author={O'Mahony, Aoife M. and Windmiller, Joshua R. and Samek, Izabela A. and Bandodkar, Amay Jairaj and Wang, Joseph}, year={2012}, month={Sep}, pages={52–55} }
 @article{yarman_peng_wu_bandodkar_gajovic-eichelmann_wollenberger_hofrichter_ullrich_scheibner_scheller_2011, title={Can peroxygenase and microperoxidase substitute cytochrome P450 in biosensors}, volume={3}, ISSN={1867-2086 1867-2094}, url={http://dx.doi.org/10.1007/s12566-011-0023-4}, DOI={10.1007/s12566-011-0023-4}, abstractNote={Aromatic peroxygenase (APO) from the basidiomycetous mushroom Agrocybe aegerita (AaeAPO) and microperoxidases (MPs) obtained from cytochrome c exhibit a broad substrate spectrum including hydroxylation of selected aromatic substrates, demethylation and epoxidation by means of hydrogen peroxide. It overlaps with that of cytochrome P450 (P450), making MPs and APOs to alternate recognition elements in biosensors for the detection of typical P450 substrates. Here, we discuss recently developed approaches using microperoxidases and peroxygenases in view of their potential to supplement P450 enzymes as recognition elements in biosensors for aromatic compounds. Starting as early as the 1970s, the direct electron transfer between electrodes and the heme group of heme peptides called microperoxidases has been used as a model of oxidoreductases. These MP-modified electrodes are used as hydrogen peroxide detectors based on the catalytic current generated by electrically contacted microperoxidase molecules. A similar catalytic reaction has been obtained for the electrode-immobilised heme protein AaeAPO. However, up to now, no MP-based sensors for substrates have been described. In this review, we present biosensors which indicate 4-nitrophenol, aniline, naphthalene and p-aminophenol based on the peroxide-dependent substrate conversion by electrode-immobilised MP and AaeAPO. In these enzyme electrodes, the signal is generated by the conversion of all substrates, thus representing in complex media an overall parameter. The performance of these sensors and their further development are discussed in comparison with P450-based electrodes.}, number={2-4}, journal={Bioanalytical Reviews}, publisher={Springer Science and Business Media LLC}, author={Yarman, Aysu and Peng, Lei and Wu, Yunhua and Bandodkar, Amay and Gajovic-Eichelmann, Nenad and Wollenberger, Ulla and Hofrichter, Martin and Ullrich, René and Scheibner, Katrin and Scheller, Frieder W.}, year={2011}, month={Aug}, pages={67–94} }
 @article{matharu_bandodkar_sumana_solanki_ekanayake_kaneto_gupta_malhotra_2009, title={Low Density Lipoprotein Detection Based on Antibody Immobilized Self-Assembled Monolayer: Investigations of Kinetic and Thermodynamic Properties}, volume={113}, ISSN={1520-6106 1520-5207}, url={http://dx.doi.org/10.1021/jp903661r}, DOI={10.1021/jp903661r}, abstractNote={Human plasma low density lipoprotein (LDL) immunosensor based on surface plasmon resonance (SPR) and quartz crystal microbalance (QCM) was fabricated by immobilizing antiapolipoprotein B (AAB) onto self-assembled monolayer (SAM) of 4-aminothiophenol (ATP). The AAB/ATP/Au immunosensor can detect LDL up to 0.252 microM (84 mg/dL) and 0.360 microM (120 mg/dL) with QCM and SPR, respectively. The SPR and QCM measurements were further utilized to study the reaction kinetics of the AAB-LDL interaction. The adsorption process involved was explored using Langmuir adsorption isotherm and Freundlich adsorption models. The thermodynamic parameters such as change in Gibb's free energy (DeltaG(ads)), change in enthalpy (DeltaH(ads)), and change in entropy (DeltaS(ads)) determined at 283, 298, and 308 K revealed that the AAB-LDL interaction is endothermic in nature and is governed by entropy. Kinetic, thermodynamic, and sticking probability studies disclosed that desorption of the water molecules from the active sites of AAB and LDL plays a key role in the interaction process and increase in temperature favors binding of LDL with the AAB/ATP/Au immunosensor. Thus, the studies were utilized to unravel the most important subprocess involved in the adsorption of LDL onto AAB-modified ATP/Au surface that may help in the fabrication of LDL immunosensors with better efficiency.}, number={43}, journal={The Journal of Physical Chemistry B}, publisher={American Chemical Society (ACS)}, author={Matharu, Zimple and Bandodkar, Amay Jairaj and Sumana, G. and Solanki, Pratima R. and Ekanayake, E. M. I. Mala and Kaneto, Keiichi and Gupta, Vinay and Malhotra, B. D.}, year={2009}, month={Oct}, pages={14405–14412} }
 @article{bandodkar_dhand_arya_pandey_malhotra_2009, title={Nanostructured conducting polymer based reagentless capacitive immunosensor}, volume={12}, ISSN={1387-2176 1572-8781}, url={http://dx.doi.org/10.1007/s10544-009-9360-2}, DOI={10.1007/s10544-009-9360-2}, abstractNote={Nanostructured polyaniline (PANI) film electrophoretically fabricated onto indium-tin-oxide (ITO) coated glass plate has been utilized for development of an immunosensor based on capacitance change of a parallel plate capacitor (PPC) by covalently immobilizing anti-human IgG (Anti-HIgG) using N-ethyl-N'-(3-dimethylaminopropyl) carbodiimide and N-hydroxysuccinimide chemistry. These fabricated PANI/ITO and Anti-HIgG/PANI/ITO plates have been characterized using scanning electron microscopy, cyclic voltammetry, differential pulse voltammetry and Fourier transform infra-red studies. The capacitance measurements indicate that dielectric medium of this biologically modified PPC (Anti-HIgG/PANI/ITO) is sensitive to HIgG in 5 - 5 x 10(5) ng mL(-1) range and has lower detection limit of 1.87 ng mL(-1). The observed results reveal that this Anti-HIgG modified PPC can be used as a robust, easy-to-use, reagentless, sensitive and selective immunosensor for estimation of human IgG.}, number={1}, journal={Biomedical Microdevices}, publisher={Springer Science and Business Media LLC}, author={Bandodkar, Amay Jairaj and Dhand, Chetna and Arya, Sunil K. and Pandey, M. K. and Malhotra, Bansi D.}, year={2009}, month={Oct}, pages={63–70} }