Towards Wearable Electrochemical Lactate Sensing using Osmotic-Capillary Microfluidic Pumping

Sweat analysis has received significant attention recently because collection of sweat is minimally-invasive, and it contains a panel of physiologically relevant biomarkers. While there is a significant progress in engineering sensor systems for sweat analysis, a few major challenges remain unaddressed, e.g. contamination due to skin surface, old sweat mixing with new sweat, loss of sweat due to evaporation, and dilution of analytes on excessive sweating. To address some of these challenges, we present a wearable biosensor patch for biofluid extraction, sampling, and quantitative sensing. The wearable biosensor patch consists of (1) a hydrogel and paper-based microfluidic device for combined osmotic and capillary pumping of sweat coupled with (2) screen-printed electrodes for analysis of lactate concentration in sweat. In this report, we present our benchtop characterization of the proposed device towards the development of a continuous and wearable lactate monitoring system. This wearable biosensor patch advances the continuous, non-invasive monitoring of human biochemistry at low sweat rates.