(95c) Doped Metal Oxide Nanowire Sensors for Chemical Detection

Metal oxides have been widely used as sensor materials for the detection of various types of chemicals. Metal oxide nanowires for chemical sensors have been shown to have higher sensitivity and faster response time compared to tin film sensors owing to their large specific surface (surface area to volume ratio). Developing nanowire sensors with a wider range of chemical selectivity is still a challenging issue. The incorporation of dopants, such as nickel (Ni), indium (In), platinum (Pt), and antimony (Sb), into metal oxides is an efficient way to significantly increase the chemical selectivity of sensors. In this research, single- or multi-segmented nanowires that include tin (Sn) segments are synthesized by electrodeposition technique using nanoporous templates. Dopants are incorporated into the sensor segment during electrodeposition. Electron microscopy (SEM and TEM) along with EDAX are used to characterize the nanowires fabricated. Either single nanowire sensor or sensor arrays are formed by using conventional microfabrication technique (photolithography and metal deposition) or dielectrophoretic (DEP) assembly technique. The nanowires are thermally annealed to convert tin (Sn) into tin oxide (SnO2) and integrated with microheaters to form a functional sensor device. Nanowire sensor arrays with different dopants are fabricated and exposed to various chemicals (including explosives). Sensors response (electrical resistance measurements) will be studied to improve and optimize the sensor performance (in terms of sensitivity, selectivity, and response time).