AuCu-CuO@rGO-based non-enzymatic electrochromic biosensor powered by ISF for wearable glucose monitoring

Glucose monitoring is critical for managing diabetes and preventing organ damage. Self-powered biosensors integrating biofuel cells (BFCs) with electrochromic materials (ECMs) can overcome the need for external power supplies and bulky analytical instruments, which is a limitation of conventional glucose meters. However, current research on BFC-ECM-based glucose sensors predominantly uses enzyme-based anodes. In this study, we developed the first wearable, disposable, non-enzymatic, self-powered electrochromic glucose sensor based on AuCu-CuO@reduced graphene oxide (rGO). The device comprises AuCu-CuO@rGO (anode) with an amorphous/crystalline heterostructure, an electrochromic Prussian blue (PB) display (cathode), and a microneedle array for minimally invasive extraction of interstitial fluid glucose. This design leverages the inherent potential difference between the oxidation onset potential of glucose and the formal potential of PB to drive electron transfer with direct colorimetric quantification without an external power source. The device exhibited a peak power density of 0.45 μW cm^-2 and an open-circuit voltage of up to 0.49 V at 12 mM glucose. The detection platform provides dual-mode results output: a semi-quantitative analysis by the naked-eye and an accurate quantification based on the red channel ratio (R/R₀) of the acquired PB display images. The quantitative mode demonstrated linear detection over a range of 4-14 mM (R² = 0.99) at 2 min. In vivo tests demonstrated that the sensor's signal trend was consistent with commercial glucose monitoring. This work provides a self-powered, non-enzymatic, and visually readable system, offering a promising approach for glucose monitoring.