SGER: A Novel Gas Sensing Platform with Tin Oxide Nanocrystals Supported on a Carbon Nanotube

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CBET-0803142ChengMiniaturized gas sensors that rapidly and accurately detect and differentiate trace amount of gases/vapors and their mixtures are extremely attractive for many applications, such as environmental monitoring, medical diagnosis, food processing, lab-on-a-chip analytical devices, and control of other industrial processes. The research objective of this proposal is to explore a novel sensing platform of a carbon nanotube (CNT) coated with SnO2 nanocrystals for miniaturized gas sensors. The sensing platform is based on our recent invention in nanoparticle assembly and promises to enable miniaturized gas sensors with superior sensitivity and flexibility to realize selectivity for multisensing capabilities. The new sensing platform based on multiwalled CNTs has been shown to sense low-concentration gases at room temperature, overcoming the well-known disadvantage of SnO2 sensors (high-temperature operation). However, the sensing performance can be significantly enhanced with semiconductor single-walled CNTs (SWCNTs) due to the relatively lower charge carrier density in these tubes. The specific goals of the project are to fabricate gas sensors with SnO2 nanocrystals-SWCNT structures and to characterize the sensing performance of the novel sensors. Effects of nanocrystal size and areal density on hybrid nanostructure properties and the sensor performance will be investigated. Major innovation of the project is the novel gas sensing platform for room-temperature sensing. The hybrid nanocrystal-CNT system as a sensing element is superior to either of the constituent components. The platform provides a radically new opportunity to engineer gas sensors with quantum-mechanical sensing attributes due to electronic coupling between the nanocrystal and the CNT. The proposed approach may enable engineering of a highly efficient single nanoparticle sensor with an ultimate sensitivity of a single molecule and with the advantage of parallel detection of a large array of analyte molecules simply by incorporating different types of nanocrystals, e.g., through doping. Broader impacts of this project are multi-faceted and far-reaching. Miniaturized sensors with superior performance and low power consumption will directly benefit society by enabling a secure and healthy living environment. The new sensing mechanism for the hybrid nanostructure sensor will lead to a new direction for improving sensor performance. The project results will enable a wide range of innovative applications of hybrid nanocrystal-CNT structures. The project will contribute to the training of graduate and undergraduate students in nanotechnology and gas sensing through their participation in the cutting-edge exploratory research and the integration of small nanotechnology projects into an existing core Mechanical Engineering senior experimentation course and a newly developed graduate-level course on nanomanufacturing. It will also contribute to educating K-12 students, teachers, and the general public in the area of nanotechnology through "Science Saturdays" in collaboration with Wisconsin Career Academy. Participation of women and minorities will be encouraged.