Development of a real-time sweat sensor using functionalized graphene oxide as an efficient electrode nanomaterial: Towards point of care sweat sensor

Human sweat is an accessible biofluid that carries essential electrolytes and metabolites which reflects the physiological condition of body. Its use in routine diagnostics is limited due to the non-availability of sensing system. , In this paper, a cost effective sweat sensor employing functionalized Graphene Oxide (FGO) with tris(hydroxymethyl)amino- methane (GO-THAM) electrodes. The functionalization step increases the interlayer spacing and introduces multiple hydroxyl groups, improving the interaction of the nanosheets with sodium and potassium ions. The fabricated device consists of a microfluidic channel coupled to the functionalized electrode and an ATmega328 microcontroller for real-time monitoring of ion-induced conductivity changes. The sensor was calibrated with artificial sweat solutions and further evaluated using sweat collected from volunteers during walking and after exercise. The recorded voltage outputs showed strong agreement with reference flame photometry measurements, demonstrating the reliability of the system. Because of its low cost, straightforward fabrication, and ability to detect Na + and K + concentrations in real time, this platform has strong potential for athletic performance assessment and future point-of-care applications.