Sweat analysis with a wearable sensing platform based on laser-induced graphene

F Vivaldi; A Dallinger; N Poma; A Bonini; D Biagini; P Salvo; F Borghi; A Tavanti; F Greco; F Di Francesco

doi:10.1063/5.0093301

Sweat analysis with a wearable sensing platform based on laser-induced graphene

APL Bioeng. 2022 Sep 19;6(3):036104. doi: 10.1063/5.0093301. eCollection 2022 Sep.

Authors

F Vivaldi, A Dallinger¹, N Poma, A Bonini², D Biagini², P Salvo³, F Borghi⁴, A Tavanti⁵, F Greco, F Di Francesco²

Affiliations

¹ Institute of Solid State Physics, NAWI Graz, Graz University of Technology, 8010 Graz, Austria.
² Department of Chemistry and Industrial Chemistry, University of Pisa, via Giuseppe Moruzzi 13, 56124 Pisa, Italy.
³ Institute of Clinical Physiology, National Research Council, via Giuseppe Moruzzi 1, 56124 Pisa, Italy.
⁴ Interdisciplinary Center for Nanostructured Materials and Interfaces, Department of Physics, University of Milan, Via Celoria 16, Milan 20133, Italy.
⁵ Department of Biology, University of Pisa, 56127 Pisa, Italy.

Abstract

The scientific community has shown increasing interest in laser scribing for the direct fabrication of conductive graphene-based tracks on different substrates. This can enable novel routes for the noninvasive analysis of biofluids (such as sweat or other noninvasive matrices), whose results can provide the rapid evaluation of a person's health status. Here, we present a wearable sensing platform based on laser induced graphene (LIG) porous electrodes scribed on a flexible polyimide sheet, which samples sweat through a paper sampler. The device is fully laser manufactured and features a two layer design with LIG-based vertical interconnect accesses. A detailed characterization of the LIG electrodes including pore size, surface groups, surface area in comparison to electroactive surface area, and the reduction behavior of different LIG types was performed. The bare LIG electrodes can detect the electrochemical oxidation of both uric acid and tyrosine. Further modification of the surface of the LIG working electrode with an indoaniline derivative [4-((4-aminophenyl)imino)-2,6-dimethoxycyclohexa-2,5-dien-1-one] enables the voltammetric measurement of pH with an almost ideal sensitivity and without interference from other analytes. Finally, electrochemical impedance spectroscopy was used to measure the concentrations of ions through the analysis of the sweat impedance. The device was successfully tested in a real case scenario, worn on the skin during a sports session. In vitro tests proved the non-cytotoxic effect of the device on the A549 cell line.