Characterization and testing of novel polarized nanomaterial textiles for ultrasensitive wireless gas sensors

A novel polarized nano-material (PNM) textile is fabricated and characterized at Ka-band (26.5 to 40 GHz) by rectangular waveguide measurements for three different polarization schemes (crossed, horizontal, and vertical polarized samples). Since carbon nanotubes were found to be ultra sensitive to different gases at extremely low concentration, a very important application is integrated gas sensors that are based on the change in the electrical properties of carbon nanotube materials induced by gas molecule adsorption. However, a systematic design methodology for high frequency gas sensors utilizing carbon nanotube materials is not yet possible due to the lack of in-depth knowledge on the material properties before and after being exposed to the gases of interests. In this study, the scattering parameters of PNM textile embedded in waveguides are measured in both room atmosphere and in ammonia/air mixture of 5% ammonia. The gas measurement show a phase shift of 10 degrees in S11 values. The impedance of the PNMs are computed from the scattering parameters in waveguide measurements, which for the first time experimentally show that CNTs can function as resonators at microwave frequencies.