Carbon nanotube and graphene based gas micro-sensors fabricated by dielectrophoresis on silicon

A gas sensor based upon an array of reduced graphene oxide (RGO) and single wall carbon nanotube (SWNT) micro-assemblies is presented. Due to the nature of their structure and exceptional surface-to-volume ratio, graphene sheets and carbon nanotubes demonstrate unparalleled chemisorption properties, providing greater sensitivities than a bulk material. Micro-assemblies of RGO platelets and SWNT´s were created on lithographically patterned electrode arrays utilizing dielectrophoresis. The resistivity of the assemblies can be tuned by adjusting the amplitude and frequency of the applied field. The completed array was tested in an enclosed chamber into which various gases were introduced (including common volatile organic compounds and simulants of nerve agents). Changes in the resistance of each micro-assembly due to chemisorption were monitored. Both types of assemblies (RGO and SWNT) demonstrated unique and repeatable responses to various organic compounds and other vapors. Consistent assembly and gas response results were achieved for sensor elements across many substrates.