Detection of Glucose Using Diamond Solution-Gate Field-Effect Transistor

The concentration of glucose was detected using an H-terminated diamond solution-gate field-effect transistor (H-diamond SGFET). The linker molecular 1-pyrenebutyric acid–N-hydroxy succinimide ester (Pyr-NHS) was introduced to modify the H-diamond surface. Then, glucose oxidase (GOD) was immobilized on the diamond surface by linker Pyr-NHS. Atomic force microscope and scanning electron microscope measurements confirmed the successful immobilization of Pyr-NHS and GOD enzyme on the H-diamond surface. The concentration of glucose was determined by the shift of gate voltage (
${V}_{\text {GS}}$
) in transfer characteristics of H-diamond SGFET. Also, the sensitivity of sensor for glucose detection was obtained as −58.69 mV/
${\text {log}}_{{10}}$
(glucose concentration) by the slope of fitting curve, which represented the relationship between
${\Delta {V}}_{\text {GS}}$
and logarithmic of glucose with concentration increasing from 1
$\times 10^{-{3}}$
to 1 M. The reusability of device was characterized by the transfer properties and small standard deviation (SD) of maximum output current (
${I}_{\text {DS(max)}}$
) in four tests, indicating excellent reusability for detection of glucose.