Screen-Printed Resistive Gas Sensors Based on Functionalized Carbon Nanotubes and Electronic Design for Selective Detection of Carbon Monoxide and Hydrogen

Often the most challenging aspect of research in nanostructured materials is getting the materials into a form where they can be manipulated without changing the desired properties of the nanomaterial. Brewer Science has developed a unique method for solving this problem by using solubilizing pi-bonders reacted with the carbon nanotubes in a superacid environment. The resulting carbon nanotubes can be dispersed in water, alcohols, and other polar solvents without the need for surfactant, producing a novel environment for the functionalization of the solubilized carbon nanotubes.<br/>Films made of these materials are remarkably conductive, achieving less than 400 Ω/square at 85% transmittance. These carbon nanotubes can be spray coated, placed in alcohols for ink-jet printing, or dispersed in glycols for screen printing. The resulting films can support short current pulses, which, by modulating their frequency, can be used to control the temperature of the film.<br/>In addition to making good inks, these dispersions can be used as a reaction medium to functionalize them with active materials, such as metal oxides, peptides, or polymers, to make them respond electronically to a targeted analyte or environment. In this talk, I will describe how we made tin(IV) oxide–functionalized carbon nanotubes and how we used our pulsed temperature control scheme to sense multiple analytes with only one screen-printed pixel by distinguishing the different optimal reaction temperatures of carbon monoxide and hydrogen.