A Novel-Structure LC Resonant Passive Wireless Sensor for NO2 Sensing

This work presents an LC resonant passive wireless gas sensor with a novel structure designed to mitigate the negative impact of substrate. The LC sensor antenna in the new structure, and the reader antenna, were designed and optimized utilizing HFSS software to improve the transfer efficiency. The superiority of the designed structure compared with general examples is highlighted and verified. The change in the substrate capacitance essentially makes no interference with the parameters of the LC sensor to be measured. The sensor for the new structure was prepared by combining etching and sputtering methods. The ZnO nanowires (NWs) were characterized to confirm their high purity and wurtzite crystal structure. The LC gas sensors demonstrated excellent wireless sensing performance, including a low detection limit of 0.5 ppm NO2, high response of 1.051 and outstanding stability at 180 °C. The newly developed sensor structure not only prevented interference from the substrate during gas sensing testing, but also expanded the choice of sensor substrates, playing a critical role in the development of sensors based on the LC resonance principle.