Flexible enzymatic biosensor based on graphene sponge for glucose detection in human sweat

The development of flexible glucose biosensors makes it possible to perform non-invasive blood glucose monitoring through wearable devices, which is of great significance for the prevention and treatment of diabetes. In this study, a flexible GOx/CTS/GS/PB (GCGP) biosensor for sweat glucose detection was fabricated, which is comprised of gold electrode, Prussian blue (PB), graphene sponge (GS) chitosan (CTS) and glucose oxidase (GOx). The GCGP biosensor realizes a high detection sensitivity of 1790 nA·mM−1·cm−2 and a low detection limit of 2.45 μM (S/N = 3) towards sweat glucose at a low potential (0.075 V, vs. Ag/AgCl) in a linear range from 8.17 to 1000 μM. Moreover, the GCGP biosensor shows high selectivity for glucose and has a good response to glucose in real sweat, which was collected from volunteers playing table tennis. The superior performance of flexible sweat glucose sensors can be due in no small part to the addition of GS. The large specific surface area and the cross-linked hierarchical porous structure of GS enable easy absorption and even distribution of a large amount of GOx. Combined with the high conductivity inherited from graphene, multiple channels for the rapid transport of electrons and ions are available. The abundant binding sites of GS provide the possibility for further composites with other functional materials to improve the performance of the flexible sweat glucose biosensor in future research.