Use of nanocomposites to increase electrical “gain” in chemical sensors

We have investigated chemical sensors by combining silicon-on-insulator complementary-metal-oxide-semiconducting microtechnology with nanotechnology. The sensing materials were single-walled carbon nanotubes and poly(3,3‴-dialkyl-quarterthiophone). The devices containing only nanotubes or pure polymer provided minimal response, whereas the nanocomposite material (1wt.% of nanotubes in the polymer) provided excellent sensitivity/selectivity to the particular analyte monitored (hydrogen, ammonia, and acetone). We observed that even small amounts of gas doping (10ppb) resulted in exponential changes in the overall conductivity profile of the nanocomposite sensor, thus anticipating an element of “gain” within the chemical sensor.