Skin-interfaced soft microfluidic systems with modular and reusable electronics for in situ capacitive sensing of sweat loss, rate and conductivity. Issue 23 (22nd October 2020)

• Record Type: Journal Article
• Authors: Hourlier-Fargette, Aurélie; Schon, Stéphanie; Xue, Yeguang; Avila, Raudel; Li, Weihua; Gao, Yiwei; Liu, Claire; Kim, Sung Bong; Raj, Milan S.; Fields, Kelsey B.; Parsons, Blake V.; Lee, KunHyuck; Lee, Jong Yoon; Chung, Ha Uk; Lee, Stephen P.; Johnson, Michael; Bandodkar, Amay J.; Gutruf, Philipp; Model, Jeffrey B.; Aranyosi, Alexander J.; Choi, Jungil; Ray, Tyler R.; Ghaffari, Roozbeh; Huang, Yonggang; Rogers, John A.
• Is Part Of: Lab on a chip. Volume 20:Issue 23(2020)
• Page Start: 4391
• Page End: 4403
• Publication Date: 2020-10-22
• Subjects: Miniature electronic equipment -- Periodicals; Combinatorial chemistry -- Periodicals; Biotechnology -- Periodicals; 543.0813
• DOI: 10.1039/d0lc00705f
• Languages: English
• ISSNs: 1473-0197

Abstract

Abstract : Stick-on electrodes capacitively coupled to single-use microfluidic channels enable contactless analysis of sweat in a soft wearable format with real-time wireless data collection. Abstract : Important insights into human health can be obtained through the non-invasive collection and detailed analysis of sweat, a biofluid that contains a wide range of essential biomarkers. Skin-interfaced microfluidic platforms, characterized by soft materials and thin geometries, offer a collection of capabilities for in situ capture, storage, and analysis of sweat and its constituents. In ambulatory uses cases, the ability to provide real-time feedback on sweat loss, rate and content, without visual inspection of the device, can be important. This paper introduces a low-profile skin-interfaced system that couples disposable microfluidic sampling devices with reusable 'stick-on' electrodes and wireless readout electronics that remain isolated from the sweat. An ultra-thin capping layer on the microfluidic platform permits high-sensitivity, contactless capacitive measurements of both sweat loss and sweat conductivity. This architecture avoids the potential for corrosion of the sensing components and eliminates the need for cleaning/sterilizing the electronics, thereby resulting in a cost-effective platform that is simple to use. Optimized electrode designs follow from a combination of extensive benchtop testing, analytical calculations and FEA simulations for two sensing configurations: (1) sweat rate and loss, and (2) sweat conductivity, which contains information about electrolyte content. Both configurations couple to a flexible, wireless electronics platform that digitizes and transmits information to Bluetooth-enabled devices. On-body field testing during physical exercise validates the performance of the system in scenarios of practical relevance to human health and performance.