Flexible Enzyme-Free Gate Engineered Bio-FET Glucose Sensor Based on Nickel-Tungstate Microcrystals

We propose highly sensitive bioelectronics glucose sensors. The design of the sensors is based on the field-effect transistor (FET) operation. Three different designs of FET-based biosensors have been proposed and compared. The circular and rectangular side-gate FETs electrolyte gated FETs (EG-FETs) and the back-gate FET (bioelectronic FET). The source, drain, and gate electrodes were deposited on the flexible PET substrate via shadow mask by dc sputtering. The sensitive material that is used as the channel of the FETs is nickel-tungstate (NiWO4) microcrystals synthesized by hydrothermal method. The measurement results show that the proposed back-gate FET (BG-FET) biosensor has a superior performance compared to other designs. The resulting back gate bioelectronic FET biosensor shows a wide detection range (0–15 mM), a detection limit of 1 nM, a sensitivity of
$650 \mu \text{A}$
.
$\mu \text{M}^{-{1}}$
, high reproducibility, good stability, and highly selectivity. There is high stability in sensor response during repeated bending cycles, with no perceptible change in FET performance observed after 100 cycles. The accurate response of the biosensor toward the real blood serum samples shows that the proposed NiWO4 back gate FET biosensors has a great potential to work as novel bioelectronic glucose test strips.