Ultra-high sensitivity pH-sensors using silicon nanowire channel dual-gate field-effect transistors fabricated by electrospun polyvinylpyrrolidone nanofibers pattern template transfer

In this study, we fabricated a silicon nanowire (SiNW)-based ultra-high-sensitivity dual-gate (DG) pH ion-sensitive field-effect transistor (pH-ISFET) using polyvinylpyrrolidone (PVP) nanofibers (NFs) as a template for SiNW fabrication. By comparing the electrical properties, capacitive coupling, pH sensitivity, and non-ideal effects, such as drift or hysteresis voltages with a silicon film channel-type DG pH-ISFET, the effectiveness of the SiNW channel was verified. The SiNW-type DG FET exhibited better electrical properties, such as higher mobility, smaller sub-threshold slopes, and larger on-off current ratios, than the conventional silicon film-type DG FET. It also showed an increased capacitive-coupling ratio between the top and bottom gates. Through pH-ISFETs, which have an extended gate connected to the fabricated DG FETs, the sensing performance of the SiNW channel and silicon film channel can be compared. In the single-gate sensing mode, the film-type and SiNW-type devices showed a sensitivity of 56.6 mV/pH and 56.3 mV/pH, respectively. Meanwhile, in the DG sensing mode, the film-type device showed a sensitivity of 938.4 mV/pH, and the SiNW-type device has a sensitivity of 1438.8 mV/pH, indicating that the pH sensitivity in the SiNW channel was significantly amplified. Non-ideal effects were also evaluated, and the SiNW-type device showed more stable performance with a smaller hysteresis voltage and drift rate than the film-type device. Therefore, pH-ISFETs based on the SiNW-type DG FET using PVP nanofiber pattern template transfer, which involve a simple and low-cost process, show their potential in future bio-sensing applications owing to their high sensitivity and excellent stability.

Automated summary

This study fabricated a SiNW-based ultra-high-sensitivity DG pH-ISFET using PVP nanofibers as a template, showing improved electrical properties and enhanced pH sensitivity. The SiNW-type device exhibited higher sensitivity and stability compared to traditional film-type devices, indicating its potential in future bio-sensing applications.