Enzyme-Functionalized Field-Effect Transistors Based on Liquid-Metal-Derived Ultrathin SnO2 Films for Glucose Detection
The increasing global incidence of diabetes necessitates advanced glucose monitoring technologies that offer continuous, painless, and user-friendly solutions. Non-invasive sweat glucose detection faces persistent challenges in sensitivity and selectivity. This work employs ultrathin SnO2 films, derived from liquid Sn-Bi alloy exfoliation and subsequent annealing, as the active channel in back-gate field-effect transistors (FETs) for glucose sensing. The defective surface hydroxyl groups serve as effective anchoring sites for stable glucose oxidase (GOX) immobilization. Enzymatic glucose oxidation generates positive charge accumulation on the SnO2 layer, modulating charge carrier density and enhancing channel current. This effect is amplified by the FET's subthreshold characteristics under negative back-gate voltage, enabling rapid, highly sensitive, and selective glucose sensing. The optimized device achieves an ultrahigh sensitivity of 1211.11 μA cm−2 μM−1 and demonstrates near-specific glucose detection in human sweat, indicating significant potential for non-invasive, continuous glucose monitoring in practical applications.