Resettable Microfluidics for Broad-Range and Prolonged Sweat Rate Sensing

Abstract

Wearable sweat sensors are emerging as promising platforms for personalized and real-time tracking of evolving health and fitness parameters. While most wearable sweat sensors focus on tracking biomarker concentration profiles, sweat secretion rate is a key metric with broad implications for assessing hydration, cardiac, and neural conditions. Here we present a wearable microfluidic sensor for continuous sweat rate measurement. A discrete impedimetric sensing scheme relying on interdigitated electrodes within a microfluidic sweat collector allows for precise and selective sweat rate measurement across a broad physiological range. Integration of a manually activated pressure pump to expel sweat from the device prevents sensor saturation and enables continuous sweat rate tracking over hours. By enabling broad range and prolonged sweat rate measurement, this platform tackles a key obstacle to realizing meaningful and actionable sweat sensing for applications in exercise physiology and medicine.

Smartphone-Based Electrochemical Systems for Glucose Monitoring in Biofluids: A Review

“…Flexible materials provide stretchable, adhesive, biocompatible and permeable matching mediums between biofluids and the monitoring system, making the monitoring process more convenient and comfortable [ 86 ]. Specifically, some flexile microfluidic patches fabricated in some studies improved the efficiency of glucose detection in biofluids [ 87 , 88 ]. Furthermore, flexible electronics enables the electrochemical detection circuit that executes electrochemical detection and records detection data to become wearable [ 89 ].…”

Paper-Based Sandwich-Structured Wearable Sensor with Sebum Filtering for Continuous Detection of Sweat pH

“…Generally, sebum secretion and sweat secretion rates vary based on the person, skin type, and physical state. According to the literature, sebum secretion rates range between 0.2 and 20 μg cm –2 min –1 and sweat secretion rates range between 0.1 and 3 mg cm –2 min –1 . − Although only an exceedingly small amount of sebum is dissolved in sweat, it can exist in sweat as suspended matter. , …”

A Soft Wearable Microfluidic Patch with Finger-Actuated Pumps and Valves for On-Demand, Longitudinal, and Multianalyte Sweat Sensing

“…In this article we describe a new class of soft wearable microfluidic devices for on-demand sweat analysis that address the above limitations by the clever incorporation of finger-actuated pumps and valves within the microfluidic architecture inspired by earlier designs primarily developed for portable applications. − A handful of recent illustrations of wearable microfluidics with embedded pumps are available in the literature. , Unlike the longitudinal, on-demand, multianalyte biochemical sensing concepts described here, the devices reported in previous publications are designed for sample collection and monitoring of average sweat rates derived by calculating the time required for filling the device with sweat. Traditional portable sensors for point-of-care diagnostics cannot provide on-demand sweat sampling capabilities comparable to our device.…”

“…32−34 A handful of recent illustrations of wearable microfluidics with embedded pumps are available in the literature. 35,36 Unlike the longitudinal, on-demand, multianalyte biochemical sensing concepts described here, the devices reported in previous publications are designed for sample collection and monitoring of average sweat rates derived by calculating the time required for filling the device with sweat. Traditional portable sensors for point-of-care diagnostics cannot provide on-demand sweat sampling capabilities comparable to our device.…”