Extended Data Fig. 4: Preparation and performance verification of SNAP-FET with Ag/AgCl side gates.
Preparation and performance verification of SNAP-FET with Ag/AgCl side gates. (a) Fabrication of In2O3 FET with integrated Ag/AgCl side-gate electrodes. Starting from conventional In2O3 FET devices, electron-beam lithography (EBL) was used to define a patterned area between the source and drain electrodes. A Cr/Au layer (3 nm / 40 nm) was deposited by thermal evaporation to form a gold pad for Ag/AgCl deposition. Subsequently, 0.1 μL of Ag/AgCl paste was drop-cast onto the distal end of the gold pad to create a prototype Ag/AgCl gate electrode, yielding In2O3 FET devices with integrated side-gate configuration. (b) Schematic diagram of the working principle of SNAP-FET with Ag/AgCl side gate. (c) Normalized signal response (ΔI/I0) measured at VGS = 215 mV (Ag/AgCl side gate) and VGS = 200 mV (Ag/AgCl external gate) of In2O3 FET biosensors. The biosensors were tested in PBS upon exposure to HE4 (1× 10-14 M) and CA125 (3.75 × 10-2 U/mL). Dots represent individual independent samples, and bars indicate mean ± standard deviation (n = 8). Statistical significance was assessed using a two-sided unpaired t-test. No significant difference was observed between the two gating configurations for either biomarker (HE4, P = 0.7718; CA125, P = 0.0808); ns indicates not significant.
