Planar Low-Cost Microwave Ring Resonator Temperature Sensor using a PDMS Active Layer

In this work, preliminary results regarding a radio frequency planar low-cost temperature sensor, with potential for integrated sensing and communications are described. The sensor is based on a ring resonator onto which a layer of PDMS is added as the sensor active layer, allowing resonant frequency shift according to varying temperature, since the dielectric constant of the PDMS changes when exposed to different temperatures. The combination of a ring resonator with a layer of PDMS on top allows the development of a thermal sensor using microwave signals, such as those used for communications. The resonant frequency changes at a rate of  1 MHz per degree Celsius. The resonant frequency of the ring resonator alone at room temperature was designed to resonate at 4 GHz. This work is proof of concept towards integrated sensing and communication components.