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. 2021 Jun 19;21(12):4213.
doi: 10.3390/s21124213.

Highly Sensitive and Selective Sodium Ion Sensor Based on Silicon Nanowire Dual Gate Field-Effect Transistor

Seong-Kun Cho  1 , Won-Ju Cho  1
Affiliations

Highly Sensitive and Selective Sodium Ion Sensor Based on Silicon Nanowire Dual Gate Field-Effect Transistor

Seong-Kun Cho et al. Sensors (Basel). .

Abstract

In this study, a highly sensitive and selective sodium ion sensor consisting of a dual-gate (DG) structured silicon nanowire (SiNW) field-effect transistor (FET) as the transducer and a sodium-selective membrane extended gate (EG) as the sensing unit was developed. The SiNW channel DG FET was fabricated through the dry etching of the silicon-on-insulator substrate by using electrospun polyvinylpyrrolidone nanofibers as a template for the SiNW pattern transfer. The selectivity and sensitivity of sodium to other ions were verified by constructing a sodium ion sensor, wherein the EG was electrically connected to the SiNW channel DG FET with a sodium-selective membrane. An extremely high sensitivity of 1464.66 mV/dec was obtained for a NaCl solution. The low sensitivities of the SiNW channel FET-based sodium ion sensor to CaCl2, KCl, and pH buffer solutions demonstrated its excellent selectivity. The reliability and stability of the sodium ion sensor were verified under non-ideal behaviors by analyzing the hysteresis and drift. Therefore, the SiNW channel DG FET-based sodium ion sensor, which comprises a sodium-selective membrane EG, can be applied to accurately detect sodium ions in the analyses of sweat or blood.

Keywords: dual-gate field-effect transistor; extended gate; silicon nanowire; sodium ion sensor; sodium-selective membrane.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
(a) Schematic of the electrospinning system. (b) Fabrication of SiNWs on an SOI substrate.
Figure 2
Figure 2
(a) Top view and (b) tilted view SEM images of the SiNWs after transferring the pattern template of the PVP NFs to the uppermost Si layer of the SOI wafer.
Figure 3
Figure 3
Schematic of the (a) SiNW channel DG FET transducer unit and the (b) sodium-selective membrane EG sensing unit.
Figure 4
Figure 4
Schematic of the (a) SG mode and (b) DG mode sensing operations.
Figure 5
Figure 5
Transfer characteristic curves for the SiNW channel DG FETs operated by the (a) top gate and (b) bottom gate. The insets display the output characteristic curves.
Figure 6
Figure 6
The fluctuation of drain current due to square wave pulse (assuming noise) applied to the voltage sweep under SG and DG operation mode.
Figure 7
Figure 7
(a) Transfer characteristic curves of the SiNW channel DG FET during the bottom gate operation with a constant top gate bias varying from +600 to −600 mV (in steps of 300 mV). (b) Variation in the top gate bias with ΔVref.
Figure 8
Figure 8
Transfer characteristic curves of the sodium ion sensor based on a SiNW channel DG FET with a sodium-selective membrane EG in various buffer solutions: SG mode operations for the (a) NaCl, (b) CaCl2, (c) KCl, and (d) pH buffer solutions, and DG mode operations for the (e) NaCl, (f) CaCl2, (g) KCl, and (h) pH buffer solutions.
Figure 9
Figure 9
Sensitivity of the sodium ion sensor based on a SiNW channel DG FET with sodium-selective membrane EG in various buffer solutions during the (a) SG mode and (b) DG mode operations.
Figure 10
Figure 10
Hysteresis effects of the sodium ion sensor based on SiNW channel DG FETs with sodium-selective membrane EG during the (a) SG mode and (b) DG mode operations.
Figure 11
Figure 11
Drift effects of the sodium ion sensor based on SiNW channel DG FETs with a sodium-selective membrane EG after exposure to a sodium electrolyte concentration of 10−4 M for 10 h during the (a) SG mode and (b) DG mode operations.
See this image and copyright information in PMC

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