Featured Publications
Jul 16, 2023
Thermoplastic Elastomers for Wireless, Skin-Interfaced Electronic, and Microfluidic Devices
Advanced Materials Technologies
Wireless, skin-interfaced electronic and microfluidic devices have the potential to replace wired, bulky, and cumbersome technologies for personal and clinical health monitoring, allowing care to extend from hospital settings to the home. For use on skin, these devices commonly employ silicone-based thermoset elastomers (TSEs) as layers that encapsulate the electronics or serve as molded microchannels for biofluid (e.g., sweat) capture, storage, and analysis. Barriers to commercial adoption of such devices include difficulties in use of these elastomers in conventional practices for mass manufacturing. Their relatively high cost and inability to allow for recycling represent additional disadvantages. By contrast, thermoplastic elastomers (TPEs) are fully compatible with industrial-scale manufacturing processes, low in cost, and recyclable. Like TSEs, TPEs are soft, stretchable, flexible, and optically transparent, while possessing other properties well-suited for applications in wireless, skin-interfaced devices. Herein, the characteristics, processing, and application techniques for three commercially available TPEs, including two thermoplastic polyurethanes as encapsulation layers for a wireless skin hydration sensor and one thermoplastic styrenic block copolymer for a microfluidic sweat analysis platform, are reported. The results demonstrate that TPEs can be effectively integrated into these classes of devices, as a compelling alternative to TSEs, as a mass-manufacturable, sustainable materials option.
Feb 23, 2023
Sweat as a diagnostic biofluid
Science
Eccrine sweat glands in the skin are key components of an ingenious system for evaporative cooling. Their action is controlled by the sympathetic nervous system in an adaptive, closed-loop manner to help maintain thermal homeostasis during physical or mental exertion or exposure to high temperatures. Sweat not only removes heat but also helps excrete other chemicals and metabolites from the body. Recent advances in engineering have enabled eccrine sweat to be used for diagnostic purposes, in the form of soft microfluidic analysis systems (1, 2) that gently adhere to the skin for in situ capture, storage, and biochemical evaluation of directly sourced microliter samples. These noninvasive technologies create a broad spectrum of possibilities for using sweat to assess health status and chemical balance, screen for disease conditions, monitor loss of essential chemical species, and detect trace toxins or exogenous agents without the need for external sample collection and analysis.
Jan 19, 2023
The Gx Sweat Patch for personalized hydration management
Nature
The Gx Sweat Patch is a wearable microfluidic sweat sensor that can be worn by athletes to monitor their sweating rate and sweat chloride concentration. Here, we highlight the commercialization of the Gx Sweat Patch, from developing and optimizing prototypes of a wearable sweat-sensing platform, to validation in competitive individual and team-sport athletes, and the challenges of commercial launch.
Aug 30, 2022
Soft, environmentally degradable microfluidic devices for measurement of sweat rate and total sweat loss and for colorimetric analysis of sweat biomarkers
EcoMat
Here, we introduce materials and fabrication techniques that bypass these concerns through biodegradable microfluidic systems with a full range of features, including measurement of sweat rate and total loss, and colorimetric analysis of biomarkers. The key components fully degrade through the enzymatic action of microorganisms in natural soil environments, or in industrial compost facilities, to yield end products with beneficial uses as fertilizers and species to improve soil health.
July 15, 2022
Skin-Interfaced Microfluidic System with Machine Learning-Enabled Image Processing of Sweat Biomarkers in Remote Settings
Advanced Materials Technologies
Dehydration has many deleterious effects on cognitive and physical performance as well as physiological function, in the context of sports, industrial work, clinical rehabilitation, and military applications. Here, an updated wearable microfluidic sweat testing system targeted for recreational athletes is presented that includes a microfluidic patch accommodating a broad range of sweating rates, and a smartphone app incorporating digital image processing algorithms to enable real-time analysis under different lighting conditions and patch orientations. Expansive field trials (n = 148 subjects) show significant correlations between the microfluidic patch and standard absorbent patch in measuring sweating rate and sweat chloride concentration during recreational exercise. This validation study demonstrates the applicability of the microfluidic patch and software platform for field testing in recreational athletes.
Nov 7, 2021
A Skin-Interfaced, Miniaturized Microfluidic Analysis and Delivery System for Colorimetric Measurements of Nutrients in Sweat and Supply of Vitamins Through the Skin
Advanced Science
Nutrients play critical roles in maintaining core physiological functions and in preventing diseases. Technologies for delivering these nutrients and for monitoring their concentrations can help to ensure proper nutritional balance. Eccrine sweat is a potentially attractive class of biofluid for monitoring purposes due to the ability to capture sweat easily and noninvasively from nearly any region of the body using skin-integrated microfluidic technologies. Here, a miniaturized system of this type is presented that allows simple, rapid colorimetric assessments of the concentrations of multiple essential nutrients in sweat, simultaneously and without any supporting electronics – vitamin C, calcium, zinc, and iron. A transdermal patch integrated directly with the microfluidics supports passive, sustained delivery of these species to the body throughout a period of wear.
Aug 5, 2021
State of Sweat: Emerging Wearable Systems for Real-Time, Noninvasive Sweat Sensing and Analytics
ACS Sensors
This perspective details recent progress in the development and translation of novel wearable sensors for personalized assessment of sweat dynamics and biomarkers, with precise sampling and real-time analysis. Sensor accuracy, system ruggedness, and large-scale deployment in remote environments represent key opportunity areas, enabling broad deployment in the context of field studies, clinical trials, and recent commercialization. On-body measurements in these contexts show good agreement compared to conventional laboratory-based sweat analysis approaches. These device demonstrations highlight the utility of biochemical sensing platforms for personalized assessment of performance, wellness, and health across a broad range of applications.
Additional publications
Thermoplastic Elastomers for Wireless, Skin-Interfaced Electronic, and Microfluidic Devices Advanced Materials Technologies (2023)
Sweat as a diagnostic biofluid (2023) Science (2023)
The Gx Sweat Patch for personalized hydration management Nature Reviews Bioengineering (2023)
Skin-Interfaced Microfluidic System with Machine Learning-Enabled Image Processing of Sweat Biomarkers in Remote Settings Advanced Materials Technologies (2022)
A Skin-Interfaced, Miniaturized Microfluidic Analysis and Delivery System for Colorimetric Measurements of Nutrients in Sweat and Supply of Vitamins Through the Skin Advanced Science (2021)
State of Sweat: Emerging Wearable Systems for Real-Time, Noninvasive Sweat Sensing and Analytics ACS Sensors (2021)
Soft, skin-interfaced sweat stickers for cystic fibrosis diagnosis and management Science Translational Medicine (2021)
Rapid Capture and Extraction of Sweat for Regional Rate and Cytokine Composition Analysis Using a Wearable Soft Microfluidic System Journal of Investigative Dermatology (2021)
Sweat-activated biocompatible batteries for epidermal electronic and microfluidic systems Nature Electronics (2020)
Skin-interfaced microfluidic system with personalized sweating rate and sweat chloride analytics for sports science applications Science Advances (2020)
Can sweat shed a light on disease severity in atopic dermatitis? Dermatology Times (2020)
Can mHealth Technology Help Mitigate the Effects of the COVID-19 Pandemic? IEEE Open Journal of Engineering in Medicine and Biology (2020)
Don’t Sweat It: The Quest for Wearable Stress Sensors Matter (2020)
Human motion component and envelope characterization via wireless wearable sensors BMC Biomedical Engineering (2020)
Soft, skin-interfaced microfluidic systems with integrated enzymatic assays for measuring the concentration of ammonia and ethanol in sweat Lab on a Chip (2020)
Waterproof, electronics-enabled, epidermal microfluidic devices for sweat collection, biomarker analysis, and thermography in aquatic settings Science Advances (2019)
Wearable Sensors for Biochemical Sweat Analysis Annual Review of Analytical Chemistry (2019)
Soft, Skin-Interfaced Microfluidic Systems with Passive Galvanic Stopwatches for Precise Chronometric Sampling of Sweat Advanced Materials (2019)
Passive sweat collection and colorimetric analysis of biomarkers relevant to kidney disorders using a soft microfluidic system Lab on a Chip (2019)
Counting Bites With Bits: Expert Workshop Addressing Calorie and Macronutrient Intake Monitoring Journal of Medical Internet Research (2019)
Soft, skin-interfaced wearable systems for sports science and analytics Current Opinion in Biomedical Engineering (2019)
Augmenting Clinical Outcome Measures of Gait and Balance with a Single Inertial Sensor in Age-Ranged Healthy Adults Sensors (Basel) (2019)
Bio-Integrated Wearable Systems: A Comprehensive Review American Chemical Society (2019)
A fluorometric skin-interfaced microfluidic device and smartphone imaging module for in situ quantitative analysis of sweat chemistry Lab on a Chip (2018)
Skin-interfaced systems for sweat collection and analytics Science Advances (2018)
Relation between blood pressure and pulse wave velocity for human arteries PNAS (2018)
Soft, skin-mounted microfluidic systems for measuring secretory fluidic pressures generated at the surface of the skin by eccrine sweat glands. Lab on a Chip (2017)
A soft, wearable microfluidic device for the capture, storage, and colorimetric sensing of sweat Science Translational Medicine (2016)