SnO2 capacitive sensor integrated with microstrip patch antenna for passive wireless detection of ethylene gas

A capacitive gas sensor using tin oxide ( SnO2) nanoparticles has been integrated with a microstrip patch antenna for detecting ethylene gas emanated from climacteric fruits. The decrease in sensor capacitance owing to the presence of ethylene (0-100 ppm) changes the antenna resonant frequency and return loss ( by 7 MHz and 9.5 dB) which can be monitored wirelessly.