Gas sensing using carbon nanotube-based resonator

Abstract

We present the design and development of a highly sensitive and fast response microwave resonant sensor for monitoring the presence of gases present in the environment. The sensor consists of a circular disk electromagnetic resonant circuit coated with multi/single-walled carbon nanotubes that are highly sensitive to adsorbed gas molecules. Trace amounts (ppb) of gases or organic solvent vapors (polar or non-polar) can be detected with high selectivity and sensitivity. The enhanced sensing properties result from a change in the effective dielectric properties of the resonator when exposed to different gas environments. In general, the resonant frequency shifts scale accordingly with the dielectric constants of the gases under test and the recovery and response times are <10 minutes. Importantly, our sensing platform does not require functionalized carbon nanotubes to enhance specificity, or wire connection to the nanotubes, making it attractive for remote sensor technology.