Improvement of glucose detection using 10 nm Al₂O₃ thin film on diamond solution-gate field-effect transistor

Glucose detection is crucial for diagnosis, prevention and treatment of diabetes mellitus. In this work, 10 nm Al₂O₃ thin film was introduced on the channel of diamond solution-gate field-effect transistor (SGFET) to improve the performance of glucose detection. AFM results show the roughness of channel surface increased after Al₂O₃ thin film deposition. Then, 1-pyrenebutyric acid-N-hydroxy succinimide ester (Pyr-NHS) and glucose oxidase (GOD) were linked on the channel. The morphology after each modification step was evaluated by SEM, and the result indicated an uneven Al₂O₃ distribution. XPS spectra further confirmed the effective modification of Pyr-NHS and GOD. In addition, the shifts of transfer characteristics for each concentration of glucose were analyzed, which illustrated a wide linear response (10^-8-10^-2 M), a high sensitivity (-44.01 mV/log₁₀[glucose concentration]) and a low detection limitation (10^-8 M). All these results show an excellent detection performance, which may provide a new idea for the design of diamond SGFET biosensor.