Plasticization of a polymer layer harnessed to a silicon microcantilever as a highly sensitive and selective means to detect nitroaromatic derivatives

A new approach to the chemo-mechanical detection of trace amounts of nitroaromatics, even in the presence of high concentrations of background materials, is presented. The detection scheme is based on the plasticization of an aminopropyl silane layer that is harnessed to a silicon beam following its reaction with nitroaromatic systems. The reaction-induced plasticization attenuates the temperature induced bending of the polymer-beam sandwich, offering a simple and very sensitive tool for the detection of nitroaromatic systems. Using this approach, it was possible to detect a sample of 100 pg TNT even in the presence of a ∼10⁹ fold excess of a background material such as acetonitrile.