Polycrystalline Silicon Nanowire Field Effect Transistor Biosensors for SARS-CoV-2 Detection

Abstract

Disease detection and monitoring play a critical role in the ongoing COVID-19 pandemic. A comprehensive detection platform that enables early virus detection can effectively stem the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In this study, a polycrystalline silicon nanowire field-effect transistor (NWFET) was developed to detect the spike protein of SARS-CoV-2. The NWFET were fabricated through the application of sidewall spacer etching to maintain a nanowire diameter of less than 100 nm. The on–off current ratio of the transistor reached 106, and its subthreshold swing was 125 mV/decade, indicating the transistor’s strong attributes and stability. The biosensor based on this transistor reached a sensitivity of 59 mV pH−1 when used to test solutions with a pH value ranging between 6 and 9. We employed the biosensor in the detection of the SARS-CoV-2 spike protein, and the results revealed that the characteristic curve gradually shifted toward the left as the antigen of spike protein progressively increased in concentration. The limit of detection was estimated to be 0.51 ag ml−1. The results of the real-time testing of the spike protein were also successful, verifying the performance and applicability of the biosensor as a rapid screening tool for SARS-CoV-2.