Detection of TNT in sulfuric acid solution by SiNWs-FET based sensor

Since the preparation of TNT is always proceed in acid solution, it is very difficult to detect TNT accurately in its production stage. TNT sensor which can work in sulfuric acid solution will be very helpful. This paper presents a SiNWs-FET based TNT sensor which can detect TNT in sulfuric acid in fast response time. The detection mechanism is based on the fact that TNT molecules can selectively bond to the amino group of nanowires, which act as grid elements and modulate the conductance of the silicon nanowires, leading to the variation of SiNWs-FET drain-source current. Our SiNWs-FET were fabricated on a (111) silicon-on-insulator (SOI) wafer using controllable silicon anisotropy etching and self-limiting oxidation. Oxygen plasma and 3-aminopropyltriethoxysilane (APTES) were employed to modify the silicon nanowires with hydroxy and amino group respectively. In aqueous solution with 0.1% dimethyl sulfoxide (DMSO) and sulfuric acid solutions, the SiNWs-FET demonstrated the high sensitive detection to TNT. These experimental results just show that the SiNWs-FET can work stably and reliably in some harsh environment even in high concentration of sulfuric acid.