A Gas Sensor Array Using Carbon Nanotubes and Microfabrication Technology

Monitoring concentrations of chemicals, gases, and vapors is a critical task in the chemical industry, power plants, automotive exhaust, environmental protection, planetary science, and numerous other situations. Chemical sensors for specific species with varying sensitivity and discrimination levels are commercially available. Common chemical sensors differ in terms of the sensing material and the nature of the property change such as electrical conductivity, optical characteristics, temperature, etc.. Some of the current sensor technologies include high temperature oxide thin-film sensors, polymer-based sensors, catalytic-based sensors, and surface acoustic wave sensors. 1 Key attributes expected of a sensor include sensitivity in the parts per million to billion ppm, ppb range where trace levels are involved, absolute discrimination, room temperature operation, low power consumption, reasonable size, volume and mass, and low cost for large-scale applications. Given such a broad set of desirable attributes and diverse application fields, sensor development is a constantly evolving research area. The newest contributions to this field are nanoscience and technology where novel nanomaterials, because of their size, large surface to volume ratio, and properties that differ from their bulk counterparts, promise to offer better performance than micro- and macrosensors. Some of the candidate nanomaterials include carbon nanotubes CNTs, 2