Resettable skin interfaced microfluidic sweat collection devices with chemesthetic hydration feedback

Jonathan T Reeder,Robin Kim,Yonggang Huang,Justin Hanson,Jungil Choi,Yeguang Xue,John A Rogers,Emily Patnaude,Raudel Avila,Amay J Bandodkar,Claire Liu,Siddharth Krishnan,Alexandra Johnson,Yujun Deng,Daniel Franklin,Olivia Prado,John Ciraldo

doi:10.1038/s41467-019-13431-8

Abstract

Recently introduced classes of thin, soft, skin-mounted microfluidic systems offer powerful capabilities for continuous, real-time monitoring of total sweat loss, sweat rate and sweat biomarkers. Although these technologies operate without the cost, complexity, size, and weight associated with active components or power sources, rehydration events can render previous measurements irrelevant and detection of anomalous physiological events, such as high sweat loss, requires user engagement to observe colorimetric responses. Here we address these limitations through monolithic systems of pinch valves and suction pumps for purging of sweat as a reset mechanism to coincide with hydration events, microstructural optics for reversible readout of sweat loss, and effervescent pumps and chemesthetic agents for automated delivery of sensory warnings of excessive sweat loss. Human subject trials demonstrate the ability of these systems to alert users to the potential for dehydration via skin sensations initiated by sweat-triggered ejection of menthol and capsaicin.

Highlights

Introduced classes of thin, soft, skin-mounted microfluidic systems offer powerful capabilities for continuous, real-time monitoring of total sweat loss, sweat rate and sweat biomarkers
Epidermal microfluidic systems for capturing, handling and locally storing sweat as it emerges from the surface of the skin offer advantages over collection techniques that use paper, hydrogel, or textile materials, due to their ability to precisely quantify local sweat loss, sweat rate, and biomarker concentration, continuously[3,4,5,6,7,8]
The results indicate that the doses lie above the lower limen for 9/12 menthol subjects and 12/16 of capsaicin subjects, with all sensations registered within 10 min of ejection

Summary

Introduction

Introduced classes of thin, soft, skin-mounted microfluidic systems offer powerful capabilities for continuous, real-time monitoring of total sweat loss, sweat rate and sweat biomarkers. The system consists of a soft, microfluidic device of polydimethylsiloxane (PDMS) that conformally mounts on the epidermis to enable the capture, storage, and manual ejection of collected sweat (Fig. 1b).

Results

Conclusion