Development of Radio-Frequency Sensors for Detection of Volatile Organic Compounds in Liquid Media

Volatile Organic Compounds (VOCs) are prominently found in our ecosystem as pollutants, causative agents, and particulate matter. The challenge is the availability of such types of sensors which operates for detection of dissolved vOC. Researchers are exploring various nanomaterials which could be useful for facilitating the process of detection. In this work, radio-frequency sensors, which are Complimentary Split Ring Resonators (CSRR) with square rings operating at a resonant frequency of around 550 MHz are used. Stannous Oxide nanoparticles (NPs) which were further functionalized with Octa-decyl-tri-chloro siloxane (OTS) are used for improved sensitivity pf the sensors. The size of these nanoparticles was ~ 15-30 nm. The change in the sensor frequency was studied by drop-casting different concentrations of functionalized nanoparticles with and without VOC. The resonance shift for acetone and butanol was found to be 16.6 MHz and 11.2 MHz while power attenuation was 4.1 dB and 2.9 dB respectively for 100 ppm concentration. Maximum shift in resonance frequency and power attenuation was obtained for ethanol which was 28.1 MHz and 5.8 dB for a concentration of 100 ppm when sensed using functionalized NPs.