A Capillary-Evaporation Micropump for Real-Time Sweat Rate Monitoring with an Electrochemical Sensor

Abstract

Sweat collection and real time monitoring of sweat rate play essential roles in physiology monitoring and assessment of an athlete’s performance during exercise. In this paper, we report a micropump for sweat simulant collection based on the capillary–evaporation effect. An electrochemical sensor is integrated into the micropump, which monitors the flow rate in real-time by detecting the current using three electrodes. The evaporation rate from micropore array, equivalent to the sweat rate, was theoretically and numerically investigated. The designed micropump yields the maximum collection rate as high as 0.235 μ L/min. In addition, the collection capability of the micropump was validated experimentally; the flow rate through the microchannel was further detected in real-time with the electrochemical sensor. The experimental maximum collection rate showed good consistency with the theoretical data. Our proposed device shows the potential for sweat collection and real-time monitoring of sweat rate, which is a promising candidate for being a wearable platform for real-time physiology and performance monitoring during exercise.

Wearable Osmotic-Capillary Patch for Prolonged Sweat Harvesting and Sensing

“…Anaerobic glycolysis compensates some of this high energy demand and increases the production of lactate (byproduct of anaerobic glycolysis), which eventually appears in sweat. , The 4 M glucose hydrogel produced a LER of ∼3.10 (nmol/cm 2 )/min (assuming constant generation rate), which corresponded to an average lactate quantity and concentration of ∼44.5 nmol ( p < 0.05) and ∼20 mM ( p < 0.05) respectively, after an hour of testing (Figure a,b). These data match well with the lactate readout of the dry rub test and existing devices reported under similar exertion (medium intensity) levels (Figure a,b). ,,,− This validates the efficient functioning of the patch, even during exercise. The evaluation of the patch performance under high-intensity exercise − is beyond the scope of this study.…”

“…The use of paper microfluidic channels can be an extremely simple and efficient approach for long-term sweat harvesting and management. Not only is paper is a readily available and inexpensive material but its porous nature and the ability to control flow rates via capillary wicking and evaporation make it very suitable as a medium to transport and manage sweat. , Evaporation-assisted passive pumping has been used effectively by researchers to develop several microfluidic devices. − Yet, to the best of our knowledge, the combined actions of passive osmotic microfluidic pumping and evaporation-assisted fluid management via paper have not been yet deployed in an operational wearable device for biomarker analysis in sweat.…”

A One-Dollar, Disposable, Paper-Based Microfluidic Chip for Real-Time Monitoring of Sweat Rate

“…The hole exposed to air is used for releasing increased air pressure caused by the entry of sweat and continuously draws sweat through the micro-channel [ 35 ]. In addition to the higher flow rate, the biggest advantage of the small hole for evaporation is that it enables convenient control of the flow rate [ 36 ]. By changing the size of the small hole, the flow rate can be easily regulated.…”

Monitoring the Covid-19 Diffusion by Combining Wearable Biosensors and Smartphones.

“…Besides, it can record the progress of patient symptoms and monitor them at home while in quarantine. The proposed system is only a preliminary prototype, and its performance can be strongly improved by using innovative two-dimensional semiconductors with higher charge carrier mobility as reported in the related literature [16][17][18][19][20][21][22][23][24][25].…”