Flexible, Stretchable Sensors for Wearable Health Monitoring: Sensing Mechanisms, Materials, Fabrication Strategies and Features

Wearable health monitoring systems have gained considerable interest in recent years owing to their tremendous promise for personal portable health watching and remote medical practices. The sensors with excellent flexibility and stretchability are crucial components that can provide health monitoring systems with the capability of continuously tracking physiological signals of human body without conspicuous uncomfortableness and invasiveness. The signals acquired by these sensors, such as body motion, heart rate, breath, skin temperature and metabolism parameter, are closely associated with personal health conditions. This review attempts to summarize the recent progress in flexible and stretchable sensors, concerning the detected health indicators, sensing mechanisms, functional materials, fabrication strategies, basic and desired features. The potential challenges and future perspectives of wearable health monitoring system are also briefly discussed.

[1]  Wenyao Xu,et al.  Smart Insole: A Wearable Sensor Device for Unobtrusive Gait Monitoring in Daily Life , 2016, IEEE Transactions on Industrial Informatics.

[2]  Xiaochen Dong,et al.  Recent progress of flexible and wearable strain sensors for human-motion monitoring , 2018 .

[3]  Timothy O'Connor,et al.  Plasticization of PEDOT:PSS by Common Additives for Mechanically Robust Organic Solar Cells and Wearable Sensors , 2015 .

[4]  Sida Luo,et al.  Direct laser writing for creating porous graphitic structures and their use for flexible and highly sensitive sensor and sensor arrays , 2016 .

[5]  Sushmee Badhulika,et al.  Solvent-free fabrication of a biodegradable all-carbon paper based field effect transistor for human motion detection through strain sensing , 2016 .

[6]  Hyung-Jun Koo,et al.  Highly Stretchable and Transparent Microfluidic Strain Sensors for Monitoring Human Body Motions. , 2015, ACS applied materials & interfaces.

[7]  Huanfen Yao,et al.  A contact lens with embedded sensor for monitoring tear glucose level. , 2011, Biosensors & bioelectronics.

[8]  Tian Jian Lu,et al.  Recent Advances in Pen‐Based Writing Electronics and their Emerging Applications , 2016 .

[9]  B. H. Weiller,et al.  Patterning and electronic tuning of laser scribed graphene for flexible all-carbon devices. , 2012, ACS nano.

[10]  Zhigang Xu,et al.  Recent advances on the development of magnesium alloys for biodegradable implants. , 2014, Acta biomaterialia.

[11]  Michael C. McAlpine,et al.  3D Printed Stretchable Tactile Sensors , 2017, Advanced materials.

[12]  S. Yao,et al.  Wearable multifunctional sensors using printed stretchable conductors made of silver nanowires. , 2014, Nanoscale.

[13]  M. Haghi,et al.  Wearable Devices in Medical Internet of Things: Scientific Research and Commercially Available Devices , 2017, Healthcare informatics research.

[14]  Yong-Lae Park,et al.  A Soft Strain Sensor Based on Ionic and Metal Liquids , 2013, IEEE Sensors Journal.

[15]  Woo Soo Kim,et al.  A Wireless Wristband Accelerometer for Monitoring of Rubber Band Exercises , 2016, IEEE Sensors Journal.

[16]  W. Kim,et al.  Stretchable RFID for Wireless Strain Sensing With Silver Nano Ink , 2014, IEEE Sensors Journal.

[17]  Babak Ziaie,et al.  Direct Laser Writing of Porous-Carbon/Silver Nanocomposite for Flexible Electronics. , 2016, ACS applied materials & interfaces.

[18]  A. Bandodkar,et al.  Advanced Materials for Printed Wearable Electrochemical Devices: A Review , 2017 .

[19]  David A. Hutchins,et al.  A Simple, Low-Cost Conductive Composite Material for 3D Printing of Electronic Sensors , 2012, PloS one.

[20]  Jing Liu,et al.  Liquid-Metal-Painted Stretchable Capacitor Sensors for Wearable Healthcare Electronics , 2016 .

[21]  Joseph Wang,et al.  Wearable salivary uric acid mouthguard biosensor with integrated wireless electronics. , 2015, Biosensors & bioelectronics.

[22]  Yajun Jiang,et al.  MoS2-based all-fiber humidity sensor for monitoring human breath with fast response and recovery , 2017 .

[23]  Wei Gao,et al.  Wearable Microsensor Array for Multiplexed Heavy Metal Monitoring of Body Fluids , 2016 .

[24]  Chunya Wang,et al.  Carbonized Cotton Fabric for High‐Performance Wearable Strain Sensors , 2017 .

[25]  Hongwei Zhu,et al.  Recent advances in wearable tactile sensors: Materials, sensing mechanisms, and device performance , 2017 .

[26]  D. Yamamoto,et al.  All-printed, planar-type multi-functional wearable flexible patch integrated with acceleration, temperature, and ECG sensors , 2017, 2017 IEEE 30th International Conference on Micro Electro Mechanical Systems (MEMS).

[27]  G. Whitesides,et al.  Paper-Based Electrical Respiration Sensor. , 2016, Angewandte Chemie.

[28]  Jidong Shi,et al.  Tactile Sensing System Based on Arrays of Graphene Woven Microfabrics: Electromechanical Behavior and Electronic Skin Application. , 2015, ACS nano.

[29]  T. Someya,et al.  Stretchable, Large‐area Organic Electronics , 2010, Advanced materials.

[30]  Amay J. Bandodkar,et al.  Self‐Healing Inks for Autonomous Repair of Printable Electrochemical Devices , 2015 .

[31]  Z. Blum,et al.  Powering electronic contact lenses: current achievements, challenges, and perspectives , 2014 .

[32]  Zheng Zhang,et al.  Flexible and printable paper-based strain sensors for wearable and large-area green electronics. , 2016, Nanoscale.

[33]  X. W. Sun,et al.  Printed all-solid flexible microsupercapacitors: towards the general route for high energy storage devices , 2014, Nanotechnology.

[34]  Jinxin Zhang,et al.  Self-powered wireless smart patch for healthcare monitoring , 2017 .

[35]  Zhenan Bao,et al.  Pursuing prosthetic electronic skin. , 2016, Nature materials.

[36]  Daniel M. Vogt,et al.  Embedded 3D Printing of Strain Sensors within Highly Stretchable Elastomers , 2014, Advanced materials.

[37]  Yi Zheng,et al.  Direct Desktop Printed-Circuits-on-Paper Flexible Electronics , 2013, Scientific Reports.

[38]  L. Beccai,et al.  Flexible Three‐Axial Force Sensor for Soft and Highly Sensitive Artificial Touch , 2014, Advanced materials.

[39]  George Pasparakis,et al.  Stimuli responsive self-healing polymers: gels, elastomers and membranes , 2017 .

[40]  Liqun Zhang,et al.  Wearable, Healable, and Adhesive Epidermal Sensors Assembled from Mussel‐Inspired Conductive Hybrid Hydrogel Framework , 2017 .

[41]  Wenzhao Jia,et al.  Wearable temporary tattoo sensor for real-time trace metal monitoring in human sweat , 2015 .

[42]  J. Kong,et al.  Simple and rapid micropatterning of conductive carbon composites and its application to elastic strain sensors , 2014 .

[43]  Amay J. Bandodkar,et al.  Wearable Biofuel Cells: A Review , 2016 .

[44]  Jing Liu,et al.  Direct Writing of Flexible Electronics through Room Temperature Liquid Metal Ink , 2012, PloS one.

[45]  Benjamin C. K. Tee,et al.  25th Anniversary Article: The Evolution of Electronic Skin (E‐Skin): A Brief History, Design Considerations, and Recent Progress , 2013, Advanced materials.

[46]  Yonglin He,et al.  Ultrafast Paper Thermometers Based on a Green Sensing Ink. , 2017, ACS sensors.

[47]  Jeonghyun Kim,et al.  An Epidermal Stimulation and Sensing Platform for Sensorimotor Prosthetic Control, Management of Lower Back Exertion, and Electrical Muscle Activation , 2016, Advanced materials.

[48]  Joseph Wang,et al.  Noninvasive Alcohol Monitoring Using a Wearable Tattoo-Based Iontophoretic-Biosensing System , 2016 .

[49]  Hiroyuki Kudo,et al.  Soft contact lens biosensor for in situ monitoring of tear glucose as non-invasive blood sugar assessment. , 2011, Talanta.

[50]  J. Lewis,et al.  Pen‐on‐Paper Flexible Electronics , 2011, Advanced materials.

[51]  Yunxia Gao,et al.  Directly Writing Resistor, Inductor and Capacitor to Composite Functional Circuits: A Super-Simple Way for Alternative Electronics , 2013, PloS one.

[52]  Xu Xie,et al.  Flexible and Stretchable 3ω Sensors for Thermal Characterization of Human Skin , 2017 .

[53]  Patricia Scully,et al.  Direct laser write process for 3D conductive carbon circuits in polyimide , 2017 .

[54]  Cara S Kosack,et al.  A guide to aid the selection of diagnostic tests , 2017, Bulletin of the World Health Organization.

[55]  Anoop C. Patil,et al.  Neural interfaces engineered via micro- and nanostructured coatings , 2017 .

[56]  T. Trung,et al.  Flexible and Stretchable Physical Sensor Integrated Platforms for Wearable Human‐Activity Monitoringand Personal Healthcare , 2016, Advanced materials.

[57]  Liwei Lin,et al.  High resolution flexible strain sensors for biological signal measurements , 2017, 2017 19th International Conference on Solid-State Sensors, Actuators and Microsystems (TRANSDUCERS).

[58]  Amay J. Bandodkar,et al.  Wearable Chemical Sensors: Present Challenges and Future Prospects , 2016 .

[59]  M. Di Rienzo,et al.  Measurement of heart rate and respiratory rate using a textile-based wearable device in heart failure patients , 2008, 2008 Computers in Cardiology.

[60]  Sam Emaminejad,et al.  Fully integrated wearable sensor arrays for multiplexed in situ perspiration analysis , 2016, Nature.

[61]  Andres A. Aguirre-Pablo,et al.  Recyclable Nonfunctionalized Paper‐Based Ultralow‐Cost Wearable Health Monitoring System , 2017 .

[62]  Takao Someya,et al.  Integration of Organic Electrochemical and Field‐Effect Transistors for Ultraflexible, High Temporal Resolution Electrophysiology Arrays , 2016, Advanced materials.

[63]  Bridget M Waller,et al.  Selection for universal facial emotion. , 2008, Emotion.

[64]  Mary M. Rodgers,et al.  Recent Advances in Wearable Sensors for Health Monitoring , 2015, IEEE Sensors Journal.

[65]  Shalini Prasad,et al.  Lancet-free and label-free diagnostics of glucose in sweat using Zinc Oxide based flexible bioelectronics , 2017 .

[66]  He Tian,et al.  High-performance sound source devices based on graphene woven fabrics , 2017 .

[67]  Dongdong Chen,et al.  Self‐Healing Materials for Next‐Generation Energy Harvesting and Storage Devices , 2017 .

[68]  Wan-Young Chung,et al.  Wireless sensor network based wearable smart shirt for ubiquitous health and activity monitoring , 2009 .

[69]  Yapei Wang,et al.  Pen-Writing Polypyrrole Arrays on Paper for Versatile Cheap Sensors , 2014 .

[70]  Philipp Michael,et al.  CuAAC-Based Click Chemistry in Self-Healing Polymers. , 2017, Accounts of chemical research.

[71]  I. Park,et al.  Ultra-stretchable and skin-mountable strain sensors using carbon nanotubes–Ecoflex nanocomposites , 2015, Nanotechnology.

[72]  Phillip Won,et al.  A soft, wearable microfluidic device for the capture, storage, and colorimetric sensing of sweat , 2016, Science Translational Medicine.

[73]  Babak A. Parviz,et al.  A contact lens with an integrated lactate sensor , 2012 .

[74]  Zhi-Gang Zhu,et al.  A Gelated Colloidal Crystal Attached Lens for Noninvasive Continuous Monitoring of Tear Glucose , 2017, Polymers.

[75]  T. Lu,et al.  Paper: A promising material for human-friendly functional wearable electronics , 2017 .

[76]  J. Justin Gooding,et al.  A balance-in-a-box: an integrated paper-based weighing balance for infant birth weight determination , 2017 .

[77]  Danick Briand,et al.  Recent Advances in Printed Sensors on Foil , 2016 .

[78]  Joseph Wang,et al.  Tattoo‐Based Wearable Electrochemical Devices: A Review , 2015 .

[79]  Yang Xu,et al.  Cytotoxicity effects of graphene and single-wall carbon nanotubes in neural phaeochromocytoma-derived PC12 cells. , 2010, ACS nano.

[80]  J. Windmiller,et al.  A potentiometric tattoo sensor for monitoring ammonium in sweat. , 2013, The Analyst.

[81]  Jan Stegenga,et al.  Exergaming for balance training of elderly: state of the art and future developments , 2013, Journal of NeuroEngineering and Rehabilitation.

[82]  Xing Xie,et al.  Paper supercapacitors by a solvent-free drawing method† , 2011 .

[83]  K. Walus,et al.  Paper as a platform for sensing applications and other devices: a review. , 2015, ACS applied materials & interfaces.

[84]  Xuewen Wang,et al.  Silk‐Molded Flexible, Ultrasensitive, and Highly Stable Electronic Skin for Monitoring Human Physiological Signals , 2014, Advanced materials.

[85]  Gang Wang,et al.  Self-Healable Gels for Use in Wearable Devices , 2017 .

[86]  Stephanie J. Benight,et al.  Stretchable and self-healing polymers and devices for electronic skin , 2013 .

[87]  Wi Hyoung Lee,et al.  Inkjet Etching of Polymers and Its Applications in Organic Electronic Devices , 2017, Polymers.

[88]  Tarek Taha,et al.  Highly Flexible Strain Sensor from Tissue Paper for Wearable Electronics , 2016 .

[89]  Yu-Te Liao,et al.  A contact lens with integrated telecommunication circuit and sensors for wireless and continuous tear glucose monitoring , 2012 .

[90]  Kai Jiang,et al.  Recent Advances in Flexible/Stretchable Supercapacitors for Wearable Electronics. , 2018, Small.

[91]  Paul Lukowicz,et al.  Textile Building Blocks: Toward Simple, Modularized, and Standardized Smart Textile , 2017, Smart Textiles.

[92]  Jie Xu,et al.  Recent Advancements in Functionalized Paper-Based Electronics. , 2016, ACS applied materials & interfaces.

[93]  Kohji Mitsubayashi,et al.  Cavitas Sensors: Contact Lens Type Sensors & Mouthguard Sensors , 2016 .

[94]  Anming Hu,et al.  Femtosecond Laser Fabrication of Cavity Microball Lens (CMBL) inside a PMMA Substrate for Super-Wide Angle Imaging. , 2015, Small.

[95]  Jin Seob Kim,et al.  Wearable Potentiometric Chloride Sweat Sensor: The Critical Role of the Salt Bridge. , 2016, Analytical chemistry.

[96]  Benjamin C. K. Tee,et al.  An electrically and mechanically self-healing composite with pressure- and flexion-sensitive properties for electronic skin applications. , 2012, Nature nanotechnology.

[97]  Zheng Liu,et al.  Flexible Sensing Electronics for Wearable/Attachable Health Monitoring. , 2017, Small.

[98]  E. Meng,et al.  High strain biocompatible polydimethylsiloxane-based conductive graphene and multiwalled carbon nanotube nanocomposite strain sensors , 2013 .

[99]  Yaping Zang,et al.  Flexible suspended gate organic thin-film transistors for ultra-sensitive pressure detection , 2015, Nature Communications.

[100]  M. Kaltenbrunner,et al.  Mechanically Adaptive Organic Transistors for Implantable Electronics , 2014, Advanced materials.

[101]  Zheng Zhang,et al.  Flexible, Cuttable, and Self-Waterproof Bending Strain Sensors Using Microcracked Gold Nanofilms@Paper Substrate. , 2017, ACS applied materials & interfaces.

[102]  Zhen Zhen,et al.  Structural engineering of gold thin films with channel cracks for ultrasensitive strain sensing , 2016 .

[103]  Jing Liu,et al.  Biomedical Implementation of Liquid Metal Ink as Drawable ECG Electrode and Skin Circuit , 2013, PloS one.

[104]  Haisheng Xia,et al.  Validation of a smart shoe for estimating foot progression angle during walking gait. , 2017, Journal of biomechanics.

[105]  Bowen Zhu,et al.  Silk Fibroin for Flexible Electronic Devices , 2016, Advanced materials.

[106]  Rezaul K. Begg,et al.  Foot Plantar Pressure Measurement System: A Review , 2012, Sensors.

[107]  Olfa Kanoun,et al.  Flexible Carbon Nanotube Films for High Performance Strain Sensors , 2014, Sensors.

[108]  Chanseok Lee,et al.  Ultrasensitive mechanical crack-based sensor inspired by the spider sensory system , 2014, Nature.

[109]  Sophie LaRochelle,et al.  Wearable Contactless Respiration Sensor Based on Multi-Material Fibers Integrated into Textile , 2017, Sensors.

[110]  Zhenan Bao,et al.  Skin-inspired electronic devices , 2014 .

[111]  Haonan Si,et al.  Flexible and Highly Sensitive Strain Sensors Fabricated by Pencil Drawn for Wearable Monitor , 2015 .

[112]  Narendra Kurra,et al.  Pencil-on-paper: electronic devices. , 2013, Lab on a chip.

[113]  Marco Dionigi,et al.  Microwave Circuits in Paper Substrates Exploiting Conductive Adhesive Tapes , 2012, IEEE Microwave and Wireless Components Letters.

[114]  Craig A. Poland,et al.  Carbon nanotubes introduced into the abdominal cavity of mice show asbestos-like pathogenicity in a pilot study. , 2008, Nature nanotechnology.

[115]  Yonggang Huang,et al.  Dynamically tunable hemispherical electronic eye camera system with adjustable zoom capability , 2011, Proceedings of the National Academy of Sciences.

[116]  Kuanmin Mao,et al.  Nanoparticle monolayer-based flexible strain gauge with ultrafast dynamic response for acoustic vibration detection , 2015, Nano Research.

[117]  Donald R McCrimmon,et al.  Biocompatible nanoscale dispersion of single-walled carbon nanotubes minimizes in vivo pulmonary toxicity. , 2010, Nano letters.

[118]  Raeed H. Chowdhury,et al.  Epidermal Electronics , 2011, Science.

[119]  Kin Liao,et al.  From cotton to wearable pressure sensor , 2015 .

[120]  Jung Woo Lee,et al.  Epidermal electronics with advanced capabilities in near-field communication. , 2015, Small.

[121]  John A Rogers,et al.  Stretchable multichannel antennas in soft wireless optoelectronic implants for optogenetics , 2016, Proceedings of the National Academy of Sciences.

[122]  Shichao Niu,et al.  Superfast and high-sensitivity printable strain sensors with bioinspired micron-scale cracks. , 2017, Nanoscale.

[123]  Daniel T H Lai,et al.  Tattoolike Polyaniline Microparticle-Doped Gold Nanowire Patches as Highly Durable Wearable Sensors. , 2015, ACS applied materials & interfaces.

[124]  Jason Heikenfeld,et al.  Non‐invasive Analyte Access and Sensing through Eccrine Sweat: Challenges and Outlook circa 2016 , 2016 .

[125]  Stephen Beirne,et al.  ‘SWEATCH’: A Wearable Platform for Harvesting and Analysing Sweat Sodium Content , 2016 .

[126]  A. M. Vinu Mohan,et al.  Merging of Thin‐ and Thick‐Film Fabrication Technologies: Toward Soft Stretchable “Island–Bridge” Devices , 2017 .

[127]  K. Hata,et al.  A stretchable carbon nanotube strain sensor for human-motion detection. , 2011, Nature nanotechnology.

[128]  Zhigang Zhu,et al.  Current and Emerging Technology for Continuous Glucose Monitoring , 2017, Sensors.

[129]  Tingting Yang,et al.  Wearable and Highly Sensitive Graphene Strain Sensors for Human Motion Monitoring , 2014 .

[130]  He Tian,et al.  An intelligent artificial throat with sound-sensing ability based on laser induced graphene , 2017, Nature Communications.

[131]  Panagiotis Polygerinos,et al.  Hysteresis Compensation for Ground Contact Force Measurement With Shoe-Embedded Air Pressure Sensors , 2016 .

[132]  R. Baughman,et al.  Carbon Nanotubes: Present and Future Commercial Applications , 2013, Science.

[133]  Miao Zhu,et al.  Ultra-sensitive graphene strain sensor for sound signal acquisition and recognition , 2015, Nano Research.

[134]  U. Chung,et al.  Highly Stretchable Resistive Pressure Sensors Using a Conductive Elastomeric Composite on a Micropyramid Array , 2014, Advanced materials.

[135]  Julian Andres Ramirez-Bautista,et al.  A Review in Detection and Monitoring Gait Disorders Using In-Shoe Plantar Measurement Systems , 2017, IEEE Reviews in Biomedical Engineering.

[136]  Yicong Zhao,et al.  Mechanisms and Materials of Flexible and Stretchable Skin Sensors , 2017, Micromachines.

[137]  Sushmee Badhulika,et al.  Low cost, flexible and biodegradable touch sensor fabricated by solvent-free processing of graphite on cellulose paper , 2017 .

[138]  Begoña García Zapirain,et al.  Wireless Prototype Based on Pressure and Bending Sensors for Measuring Gate Quality , 2013, Sensors.

[139]  Wenzhao Jia,et al.  Non-invasive mouthguard biosensor for continuous salivary monitoring of metabolites. , 2014, The Analyst.

[140]  Boris Murmann,et al.  Highly stretchable polymer semiconductor films through the nanoconfinement effect , 2017, Science.

[141]  Chunya Wang,et al.  Carbonized silk georgette as an ultrasensitive wearable strain sensor for full-range human activity monitoring , 2017 .

[142]  Zhen Zhen,et al.  Foldable and electrically stable graphene film resistors prepared by vacuum filtration for flexible electronics , 2016 .

[143]  Hyun-Ho Yang,et al.  A simple breathing rate-sensing method exploiting a temporarily condensed water layer formed on an oxidized surface , 2015 .

[144]  Kun Dai,et al.  The effect of filler dimensionality on the electromechanical performance of polydimethylsiloxane based conductive nanocomposites for flexible strain sensors , 2017 .

[145]  Yonggang Huang,et al.  Ultrathin conformal devices for precise and continuous thermal characterization of human skin. , 2013, Nature materials.

[146]  Wenzhao Jia,et al.  Tattoo-based potentiometric ion-selective sensors for epidermal pH monitoring. , 2013, The Analyst.

[147]  Xuan Wu,et al.  Selectively plated stretchable liquid metal wires for transparent electronics , 2015 .

[148]  Woo Soo Kim,et al.  Instrumented rubber insole for plantar pressure sensing , 2015 .

[149]  Sam Emaminejad,et al.  A Wearable Electrochemical Platform for Noninvasive Simultaneous Monitoring of Ca(2+) and pH. , 2016, ACS nano.

[150]  Kin Fong Lei,et al.  Development of graphene-based sensors on paper substrate for the measurement of pH value of analyte , 2016, BioChip Journal.

[151]  Fabio Terzi,et al.  A paper-based platform with a pencil-drawn dual amperometric detector for the rapid quantification of ortho-diphenols in extravirgin olive oil. , 2017, Analytica chimica acta.

[152]  P. Leleux,et al.  Highly Conformable Conducting Polymer Electrodes for In Vivo Recordings , 2011, Advanced materials.

[153]  Kuang-Chao Fan,et al.  Flexible Temperature Sensor Array Based on a Graphite-Polydimethylsiloxane Composite , 2010, Sensors.

[154]  G Parati,et al.  Validation of a flexible and innovative platform for the home monitoring of heart failure patients: Preliminary results , 2009, 2009 36th Annual Computers in Cardiology Conference (CinC).

[155]  R. Dahiya,et al.  Printable stretchable interconnects , 2017 .

[156]  He Tian,et al.  Tunable and wearable high performance strain sensors based on laser patterned graphene flakes , 2016, 2016 IEEE International Electron Devices Meeting (IEDM).

[157]  Andrea Pucci,et al.  A temperature sensor based on a MWCNT/SEBS nanocomposite , 2012 .

[158]  Shuoran Chen,et al.  Nanoparticle Based Curve Arrays for Multirecognition Flexible Electronics , 2016, Advanced materials.

[159]  Libin Liu,et al.  Review of recent achievements in self-healing conductive materials and their applications , 2017, Journal of Materials Science.

[160]  Sandeep Kumar Jha,et al.  A paper strip based non-invasive glucose biosensor for salivary analysis. , 2015, Biosensors & bioelectronics.

[161]  Shinya Kano,et al.  Fast-Response and Flexible Nanocrystal-Based Humidity Sensor for Monitoring Human Respiration and Water Evaporation on Skin. , 2017, ACS sensors.

[162]  Ming Xu,et al.  From wheat bran derived carbonaceous materials to a highly stretchable and durable strain sensor , 2017 .

[163]  Jason Heikenfeld,et al.  Bioanalytical devices: Technological leap for sweat sensing , 2016, Nature.

[164]  ZhangYuanfeng,et al.  Highly Sensitive Flexible Printed Accelerometer System for Monitoring Vital Signs , 2014 .

[165]  Sergey Shleev,et al.  Miniature biofuel cell as a potential power source for glucose-sensing contact lenses. , 2013, Analytical chemistry.

[166]  Alan S Campbell,et al.  Wearable non-invasive epidermal glucose sensors: A review. , 2018, Talanta.

[167]  Majid Sarrafzadeh,et al.  Designing a Robust Activity Recognition Framework for Health and Exergaming Using Wearable Sensors , 2014, IEEE Journal of Biomedical and Health Informatics.

[168]  Joseph Wang,et al.  A wearable chemical–electrophysiological hybrid biosensing system for real-time health and fitness monitoring , 2016, Nature Communications.

[169]  Yong Lin,et al.  Ultrasensitive Cracking-Assisted Strain Sensors Based on Silver Nanowires/Graphene Hybrid Particles. , 2016, ACS applied materials & interfaces.

[170]  Hye Rim Cho,et al.  A graphene-based electrochemical device with thermoresponsive microneedles for diabetes monitoring and therapy. , 2016, Nature nanotechnology.

[171]  Wenzhao Jia,et al.  Biocompatible Enzymatic Roller Pens for Direct Writing of Biocatalytic Materials: “Do‐it‐Yourself” Electrochemical Biosensors , 2015, Advanced healthcare materials.

[172]  J. Tour,et al.  Laser-induced porous graphene films from commercial polymers , 2014, Nature Communications.

[173]  Aaron D. Mazzeo,et al.  Paper‐Based, Capacitive Touch Pads , 2012, Advanced materials.

[174]  Y. Rim,et al.  Recent Progress in Materials and Devices toward Printable and Flexible Sensors , 2016, Advanced materials.

[175]  H. Zeng,et al.  Nanowire-based transparent conductors for flexible electronics and optoelectronics. , 2017, Science bulletin.

[176]  Yonggang Huang,et al.  Materials and Mechanics for Stretchable Electronics , 2010, Science.

[177]  Richard Guy.  Diagnostic devices: Managing diabetes through the skin. , 2016, Nature nanotechnology.

[178]  Yong-Hoon Kim,et al.  Highly Sensitive Textile Strain Sensors and Wireless User-Interface Devices Using All-Polymeric Conducting Fibers. , 2017, ACS applied materials & interfaces.

[179]  Ying Chen,et al.  Epidermal Inorganic Optoelectronics for Blood Oxygen Measurement , 2017, Advanced healthcare materials.

[180]  Inkyu Park,et al.  Sensitive and stable strain sensors based on the wavy structured electrodes , 2014, 14th IEEE International Conference on Nanotechnology.

[181]  Guang-Zhong Yang,et al.  A wearable multisensing patch for continuous sweat monitoring. , 2017, Biosensors & bioelectronics.

[182]  Hye Rim Cho,et al.  Wearable/disposable sweat-based glucose monitoring device with multistage transdermal drug delivery module , 2017, Science Advances.

[183]  Dedy H. B. Wicaksono,et al.  Proprioceptive Sensing System for Therapy Assessment Using Cotton Fabric-Based Biomedical Microelectromechanical System , 2014, IEEE Sensors Journal.

[184]  Yong Lin,et al.  Silver nanowires coated on cotton for flexible pressure sensors , 2016 .

[185]  Dmitry Pankratov,et al.  Tear Based Bioelectronics , 2016 .

[186]  G. Oberdörster,et al.  Safety assessment for nanotechnology and nanomedicine: concepts of nanotoxicology , 2010, Journal of internal medicine.

[187]  Jinseok Lee,et al.  Graphite Based Electrode for ECG Monitoring: Evaluation under Freshwater and Saltwater Conditions , 2016, Sensors.

[188]  Barbara Jasiewicz,et al.  Measuring of foot plantar pressure—possible applications in quantitative analysis of human body mobility , 2017 .

[189]  N. Sottos,et al.  Autonomic healing of polymer composites , 2001, Nature.

[190]  William R. Heineman,et al.  Revolutionizing biodegradable metals , 2009 .

[191]  Yi Zheng,et al.  Personal electronics printing via tapping mode composite liquid metal ink delivery and adhesion mechanism , 2014, Scientific Reports.

[192]  I. Park,et al.  Highly stretchable and sensitive strain sensor based on silver nanowire-elastomer nanocomposite. , 2014, ACS nano.

[193]  Lu Yin,et al.  All-printed magnetically self-healing electrochemical devices , 2016, Science Advances.

[194]  I. Park,et al.  Stretchable, Skin‐Mountable, and Wearable Strain Sensors and Their Potential Applications: A Review , 2016 .

[195]  Eduardo Palermo,et al.  Gait Partitioning Methods: A Systematic Review , 2016, Sensors.

[196]  Hongwei Zhou,et al.  A flexible and degradable paper-based strain sensor with low cost , 2017 .

[197]  Ruo-Zhou Li,et al.  Direct writing on paper of foldable capacitive touch pads with silver nanowire inks. , 2014, ACS applied materials & interfaces.

[198]  Guoliang Yuan,et al.  Highly Stretchable, Ultrasensitive, and Wearable Strain Sensors Based on Facilely Prepared Reduced Graphene Oxide Woven Fabrics in an Ethanol Flame. , 2017, ACS applied materials & interfaces.

[199]  Yu-Te Liao,et al.  A 3-$\mu\hbox{W}$ CMOS Glucose Sensor for Wireless Contact-Lens Tear Glucose Monitoring , 2012, IEEE Journal of Solid-State Circuits.

[200]  Wenzhao Jia,et al.  Tattoo-based noninvasive glucose monitoring: a proof-of-concept study. , 2015, Analytical chemistry.

[201]  T. Someya,et al.  Conformable, flexible, large-area networks of pressure and thermal sensors with organic transistor active matrixes. , 2005, Proceedings of the National Academy of Sciences of the United States of America.

[202]  Woo Soo Kim,et al.  Design optimized membrane-based flexible paper accelerometer with silver nano ink , 2013 .

[203]  Yan Liu,et al.  Design and Test of a Soft Plantar Force Measurement System for Gait Detection , 2012, Sensors.

[204]  Sushmee Badhulika,et al.  Flexible, eco-friendly and highly sensitive paper antenna based electromechanical sensor for wireless human motion detection and structural health monitoring , 2016 .

[205]  Xiaofeng Wang,et al.  A Self-Powered Insole for Human Motion Recognition , 2016, Sensors.

[206]  John A Rogers,et al.  Soft, skin-mounted microfluidic systems for measuring secretory fluidic pressures generated at the surface of the skin by eccrine sweat glands. , 2017, Lab on a chip.

[207]  Feng Xu,et al.  Liquid on Paper: Rapid Prototyping of Soft Functional Components for Paper Electronics , 2015, Scientific Reports.

[208]  Raja Ghosh,et al.  Paper-Based, Hand-Drawn Free Chlorine Sensor with Poly(3,4-ethylenedioxythiophene):Poly(styrenesulfonate). , 2016, Analytical chemistry.

[209]  B. Ju,et al.  Highly Stretchable and Waterproof Electroluminescence Device Based on Superstable Stretchable Transparent Electrode. , 2017, ACS applied materials & interfaces.

[210]  Warakorn Charoensuk,et al.  Development of plantar pressure measurement using in telerehabilitation system for patient movement rehabilitation , 2017, 2017 18th International Conference on Advanced Robotics (ICAR).

[211]  Wang Luheng,et al.  Influence of carbon black concentration on piezoresistivity for carbon-black-filled silicone rubber composite , 2009 .

[212]  Dermot Diamond,et al.  A potentiometric disposable sensor strip for measuring pH in saliva , 2014 .

[213]  Yusuke Kuroki,et al.  Mouthguard biosensor with telemetry system for monitoring of saliva glucose: A novel cavitas sensor. , 2016, Biosensors & bioelectronics.