Graphene electrochemical transistor incorporated with gel electrolyte for wearable and non-invasive glucose monitoring

With the rapid development of wearable electronic devices, health monitoring is undergoing a fundamental shift from hospital-centered treatment to patient-centered diagnosis. Solution-gated graphene transistors provide an effective platform for developing high-sensitivity wearable devices due to their unique signal amplification, low energy consumption, and compatibility for miniaturization. However, it is still a major challenge to perform real-time sweat composition monitoring directly on the dry skin surface. In this work, a skin-based flexible gel electrolyte graphene transistor (GEGT) was successfully designed and fabricated for glucose detection, consisting of a gate electrode decorated with Au nanoparticles modified reduced graphene oxide (AuNPs/RGO) nanocomposites and a monolayer graphene channel. Glycerin gel was used to replace the traditional liquid electrolyte, not only could better fit the human skin, but also play the role of fluid collection, providing stable testing conditions for the sensor. Based on the high electron mobility of graphene channel and the excellent electrocatalytic performance of AuNPs/RGO nanocomposites, the constructed GEGT sensor exhibits excellent sensing performance for glucose with good selectivity, low operating voltage (0.5 V), wide detection range (10 nM - 25 mM), and low detection limit (10 nM). The device maintains stable performance after up to 1000 bending cycles with a bending radius of 4 mm. In addition, the GEGT sensor displays good accuracy in sweat detection and sensitive dynamic response during actual wearing, which provides a guarantee for the construction of wearable transistor devices and real-time health tracking.