An e-nose concept based on semiconductor-assisted field ionization and gaseous discharge on arrays of whiskered nanowires

Electronic nose systems employ an array of gas detectors each tailored to respond differently to a range of odors. In the presence of a particular gaseous compound, the responses of sensors form a signature that is analyzed in the signal transduction process. The gas sensing cells operate by a variety of different mechanisms, but generally, catalyst based sensors suffer from issues such as poor specificity, slow response time, and irreversibility. This work introduces a novel approach towards instantaneous and selective discrimination of gases based on their unique ionization properties: electric breakdown voltage and field ionization current-voltage characteristic. Synthesized gold and silicon nanowires, covered with sharp nanoscale whiskers, exhibited anomalously strong discharge and field ionization characteristics at very low bias voltages. The anomalous field ionization phenomenon was attributed to the combination of geometric field enhancement and the presence of localized surface states at the surface of the emitters.