Novel millimeter-wave gas sensor using dielectric resonator with sensitive layer on TiO2

A new generation of gas sensors that operates in millimeter-wave frequency range is presented. The sensor uses a dielectric resonator operating with whispering-gallery modes. Here the dielectric resonator is covered by TiO₂ thin film as sensitive layer. A gas or humidity adsorption makes the TiO₂ dielectric permittivity changing and such changing modifies the resonant frequencies of high-Q whispering-gallery modes within the dielectric resonator. From the measurement of these resonant frequencies the humidity concentration is derived. Here, the proof of concept is demonstrated through full wave electromagnetic simulations. This humidity (gas) sensor can be remotely interrogated and has great potential for wireless sensors network applications.