Control of sensitivity in metal oxide electrolyte gated field-effect transistor-based glucose sensor by electronegativity modulation

Abstract

In this study, the sensitivity of electrolyte-gated field-effect transistor-based glucose sensors using oxide semiconductor materials was controlled via electronegativity modulation. By controlling the enzymatic reaction between glucose and glucose oxidase, which is affected by the surface potential, the sensitivity of the glucose sensor can be effectively adjusted. To evaluate the sensitivity characteristics of the glucose sensor according to electronegativity control, devices were fabricated based on InO through Ga and Zn doping. The results confirmed that the specific sensitivity range could be adjusted by increasing the electronegativity. In addition, density functional theory calculations, confirmed that the attachment energy of the surface-functionalized material and the enzyme binding energy in the surface-functionalized thin film can be modulated depending on the electronegativity difference. The dissociation constant was controlled in both directions by doping with metal cations with larger(Ga, 1.81) or smaller(Zn, 1.65) electronegativities in InO(In, 1.78). We expect that this study will provide a simple method for the gradual and bidirectional control of the glucose sensitivity region.

Keywords: Density functional theory (DFT); Electronegativity; Glucose sensor; InGaO; InO; InZnO.

Fig. 1

(a) Scheme of surface functionalization (b) Topologies of the InGaO, InO, and InZnO thin films before and after surface functionalization. (c) C 1s, N 1s, and O 1s XPS spectra of InGaO, InO, and InZnO thin films before and after surface functionalization. (d) XPS spectra showing the deconvolution of C 1s and N 1s of the surface-functionalized InGaO, InO, and InZnO thin films.

Fig. 2

(a) Diagram of the fabricated metal-oxide EGFETs-based glucose sensor device. The inset image shows a top view of the attached PDMS wall and the sensing method. (b) Characteristics of the transfer curves (I_DS-V_GS, Ag/AgCl) of InGaO (blue circle), InO (black circle), and InZnO (red circle) EGFETs-based devices in 1× PBS solution. (c) Characteristics of the transfer curves (I_DS-V_GS) of InGaO (blue circle), InO (black circle), and InZnO (red circle) devices in air.

Fig. 3

(a) Response voltage and (b) calibrated response voltage according to glucose concentration of the InGaO, InO, and InZnO EGFET-based devices in 1× PBS.

Fig. 4

Reaction energy diagram at 0 eV (Ref.; InO) for the immobilization of the glucose oxidase (GO_x) enzyme in three different samples.