Skin-interfaced microfluidic system with personalized sweating rate and sweat chloride analytics for sports science applications

Abstract

Advanced capabilities in noninvasive, in situ monitoring of sweating rate and sweat electrolyte losses could enable real-time personalized fluid-electrolyte intake recommendations. Established sweat analysis techniques using absorbent patches require post-collection harvesting and benchtop analysis of sweat and are thus impractical for ambulatory use. Here, we introduce a skin-interfaced wearable microfluidic device and smartphone image processing platform that enable analysis of regional sweating rate and sweat chloride concentration ([Cl−]). Systematic studies (n = 312 athletes) establish significant correlations for regional sweating rate and sweat [Cl−] in a controlled environment and during competitive sports under varying environmental conditions. The regional sweating rate and sweat [Cl−] results serve as inputs to algorithms implemented on a smartphone software application that predicts whole-body sweating rate and sweat [Cl−]. This low-cost wearable sensing approach could improve the accessibility of physiological insights available to sports scientists, practitioners, and athletes to inform hydration strategies in real-world ambulatory settings.

Wearable Sweat Loss Measuring Devices: From the Role of Sweat Loss to Advanced Mechanisms and Designs

“…In this process, a qualitative result might be simply obtained by the naked eye, and a quantitative result would require volumetric labels marked in devices [ 176 ] or a secondary detection device (e.g., smartphone). [ 177 ] Moreover, colorimetric measurement of sweat loss does not require rigid electronic units for signal transduction; therefore, the overall device structure can be designed to be softer than other microfluidics‐based SLMDs. As such, many researchers have applied colorimetry to wearable microfluidics to measure sweat loss.…”

“…In addition, this class of SLMDs does not require careful control and calibration of ambient conditions for accurate readings, such as lighting conditions, which have an inevitable effect on colorimetry. [ 176 , 177 , 178 , 187 ] Although the above capability is critical for continuous and accurate measurement of sweat loss, there are trade‐offs in power consumption, production complexity, device footprint, and flexibility. [ 188 ] Generally, the transduction electrical signal used in microfluidics‐based SLMDs includes conductivity (resistance), admittance (impedance), and capacitance.…”

Hybrid Technologies Combining Solid-State Sensors and Paper/Fabric Fluidics for Wearable Analytical Devices

“…Reprinted with permission from [ 25 ] for panel ( a ). Reprinted with permission from [ 24 ], Copyright 2020 American Association for the Advancement of Science for panel ( b ).…”

“…The device components are shown in Figure 2 b. It provides a colorimetric feedback measurement of sweat rate, fluid loss, and sodium loss in real time [ 24 ].…”

Potential use of new cooling technologies during Tokyo 2020 Olympics and associated ethical dilemmas

“…Having access to real-time biodata monitoring (e.g., core temperature [9] or sweat [10]) during competition raises the conundrum related to the potential decision to withdraw athlete/s from competition on medical grounds. For example, should the medical race director or/an athlete support team withdraw a marathon runner showing signs of EHS (i.e., very high core temperature and an asymmetrical gait) at the final stages of a race or let the athlete attempt to finish potentially causing the athlete life threatening health issues?…”