A Composite Gas-Phase Explosives Sensor with Frequency-Resistance Dual-Signal Display Based on Surface Acoustic Wave

The surface acoustic wave (SAW) technology has been widely used for hazardous gas detection, but the low sensitivity, poor selectivity, long response/recovery time, and signal "false positives" of the sensors have limited its application for gas -phase explosives detection. In this paper, a composite gas-phase explosives sensor with frequency-resistance dual-signal display was designed by transferring 25 layers of graphene (rGO) in the sensing area of the SAW device and coupling p-aminothiophenol (PATP)-modified gold nanoparticles (AuNPs). The rGO:AuNP/ PATP-SAW sensor shows signal response from two signal dimensions, frequency and resistance, to 0.1-80 ppm TNT gas with a low detection limit (DL) of 41.2 ppb. The composite sensor has a short response/recovery time (9.8 s/27.1 s) with good selectivity, repeatability, and stability. The excellent gas-sensitive performance of the rGO:AuNP/PATP-SAW sensor was attributed to the fact that PATP provides a large number of selective capture groups, which are enriched in the sensing area by the presence of multiple strong interactions with 2,4,6-trinitrotoluene (TNT) molecules. This work will provide scientific guidance for the engineering promotion of surface acoustic wave gas-phase explosives sensors.