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Thursday, May 14, 2009
3:00 PM (reception to follow)
Understanding and tuning the molecular interaction with single walled carbon nanotubes for gas sensing applications
Chang Young Lee, MIT
Single walled carbon nanotubes (SWNT) are unique materials with high surface to volume ratio and all atoms residing on the surface. The one-dimensional electronic structure of SWNT is readily disrupted even by single adsorption events. Therefore, one of the promising applications of these materials has been sorption-based sensor utilizing the exterior of the SWNT. In this
presentation, our efforts on resolving two major issues of the SWNT gas sensors will be discussed.
1) Reversibility: Majority of the SWNT sensors exhibit irreversible sensor responses meaning that flushing the environment with an analyte-free gas does not completely remove the analytes from the sensor. The irreversibility is a major cause of sensor failure and also limits long term operation of the sensor. We show for the first time the irreversible-to-reversible transition via simple surface amine chemistry.
2) Selectivity: We have integrated our reversible sensors with micro-fabricated gas chromatographic (GC) column. The platform benefits from the separation capability of the GC, an analytical standard for the detection of diverse classes of organic molecules. Our approach potentially eliminates the need to engineer selective binding sites for small molecule analytes for SWNT, a difficult problem only solved for specialized cases.