I-Corps: Efficient nanowire based gas sensor

University Of North Texas, Denton TX

Investigators

Abstract

The broader impact/commercial potential of this I-Corps project is the development of a sensor platform that can monitor the presence of toxic gases in the environment. The device is intended for a wide range of applications ranging from its use in the oil and gas industry to its use as breath analyzers with applications in law and order as well as in health related fields. The proposed nanoscale device will result in relatively cheap and reliable gas sensors that can be used around gas extraction sites to monitor extremely small concentrations of toxic gases like sulphur dioxide, methane, carbon-monoxide, ammonia and hydrogen. They can also be mounted in select areas in schools and hospitals. Medical personnel could use the sensor to test the quality of exhaled air to detect high levels of nitric oxide (high levels indicative of asthma), sulfur (high levels indicative of liver dysfunction) and acetone (high levels in diabetic patients). This I-Corps project proposes to use one-dimensional nanowires as sensing elements, working on the principle that the nanowire resistance changes as its surface is modified by adsorbed gas molecules. With lengths of several tens of microns and diameters in the range of nanometers, nanowires have large surface-to-volume ratio. Hence a large number of surface sites will be available on each nanowire to facilitate surface reactions with the adsorbed gas molecules. The project is based on successful experiments where significant changes in the electrical conductance of individual nanowires were measured within several seconds of exposure to gases like ammonia, methanol, chlorine, hydrogen, and sulfur. The sensing mechanism is dominated by changes in the nanowire channel conductance caused by a change in the energy band structure when gas molecules are adsorbed on the nanowire surface. The nanoscale sensors are expected to be highly sensitive, with faster responses and can operate at room temperature, requiring low operating power. To increase gas selectivity, additional features can be added to the nanowire surface. Arrays of such nanowires mounted on a single chip will result in a highly versatile device that can be used for monitoring and sensing toxic gases in our immediate environment.