Millimeter wave carbon nanotube gas sensor

This Letter reports experimental observations regarding the significant changes in the transmission modulus and phase of the propagating microwave signals up to 110 GHz in a micromachined coplanar waveguide supported on a dielectric membrane with a thickness of 1.4 mu m filled with a mixture of carbon nanotubes when exposed to nitrogen gas. These large shifts of amplitude and phase of microwave signals due to gas absorption represent the experimental basis on which a miniature wireless gas sensor could be implemented. (c) 2007 American Institute of Physics.