Polymeric Sensing Material-Based Selectivity-Enhanced RF Resonant Cavity Sensor for Volatile Organic Compound (VOC) Detection

This paper presents a novel approach to in-line chemical gas flow monitoring, employing a high-Q RF resonator coated with a polymeric sensing material. The polymeric sensing materials employed are OV-275 and P25DMA doped with 20% NiO. These materials are known to be responsive against various VCOs, and are individually coated on the post of a combline cavity resonator to help functionalize the sensor against specific analytes. The input of the resonator was deliberately designed to achieve the minimal loading to maximize the loaded Q of the resonator, thereby improving its sensitivity near its $f_{0}$. The OV-275 sensor demonstrates sensitivity of 2.332 mdB/ppm and 0.348 mdB/ppm to acetone and benzene exposure, respectively. Similarly, the P25DMA sensor has a sensitivity of 0.199 mdB/ppm and 0.764 mdB/ppm to acetone and benzene, respectively.