Three-Dimensional Integrated Ultra-Low Volume Passive Microfluidics With Ion Sensitive Field Effect Transistors For Multi-Parameter Wearable Sweat Analyzers

• Published in: ACS nano 2018-12
• Main Authors: Garcia-Cordero, Erick, Bellando, Francesco, Zhang, Junrui, Wildhaber, Fabien, Longo, Johan, Guërin, Hoel, Ionescu, Adrian M
• Format: Article
• Language: English
• ISSN: 1936-086X
• DOI: 10.1021/acsnano.8b07413

Wearable systems could offer noninvasive and real-time solutions for monitoring of biomarkers in human sweat as an alternative to blood testing. Recent studies have demonstrated that the concentration of certain biomarkers in sweat, can be directly correlated to their concentrations in blood, making sweat a trusted biofluid candidate for non-invasive diagnostics. We introduce a wearable sweat sensing system to track biochemical information at the surface of the skin in real time. This system heterogeneously integrates on a single Si chip state-of-the-art ISFET sensor technology with a biocompatible microfluidic interface, to deliver the first "Lab-on-skinTM" sensing platform. The full process for fabrication of this system is achieved by standard semiconductor fabrication procedures. The system is capable of collecting small volumes of sweat from the skin of the user, and posteriorly driving the biofluid, by capillary action, to a set of functionalized ISFETs for analysis of pH level and Na+ and K+ concentration. Drop-casted Ion Sensing Membranes (ISM) on the different sets of sensors enables multi-parameters analysis on the same chip, with negligible cross-sensitivities, while a miniaturized Quasi-Reference Electrode (QRE) sets a stable analyte potential, avoiding the use of a cumbersome external Reference Electrode (RE). We believe our findings can lead to continuous monitoring of the sweat composition, with applications ranging from medicine to training optimization.