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NO2 Detection Using Microcantilever Based Potentiometry
Department of Electrical Engineering, University of South Carolina, Columbia, SC29208, USA
USC Nanocenter, University of South Carolina, Columbia, SC29208, USA
* Author to whom correspondence should be addressed.
Received: 1 July 2008; in revised form: 1 October 2008 / Accepted: 10 October 2008 / Published: 12 November 2008
Abstract: A highly sensitive and novel sensor platform for gases and volatile chemicals using microcantilever based potentiometry is reported. A resonant cantilever is used to detect the changes in surface work functions of functionalized substrates caused by adsorption of target gas molecules. Surface work function (SWF) changes were measured for different functionalization layers made of transition metal oxide thin films with the flow of NO2. The rate of change in SWF for In2O3 and SnO2 were found to be ~80 and ~100 μV/sec, respectively, for 70 ppm NO2. A sensitivity of 64 μV/sec for SWF change was also found for 70 ppm NO2 concentration for isolated clusters of ZnO nanowires, indicating that this technique is applicable even for nano-clusters of sensing materials where amperometric detection is impossible due to material discontinuity. NO2 detection as low as 400 ppb was possible using highly insulating In2O3 and SnO2 thin films (resistivity > 1 TΩ/⎕). Two different forms of nano scale graphite were compared with the transition oxide based functionalization layer for sensing sub-ppm NO2 sensing. It was observed that nanostructured graphite (NG) shows much higher sensitivity and lower response time than transition metal oxides.
Keywords: Microcantilever; potentiometry; surface work function; nanoscale graphite; NO2 sensor
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MDPI and ACS Style
Qazi, M.; Koley, G. NO2 Detection Using Microcantilever Based Potentiometry. Sensors 2008, 8, 7144-7156.
Qazi M, Koley G. NO2 Detection Using Microcantilever Based Potentiometry. Sensors. 2008; 8(11):7144-7156.
Qazi, Muhammad; Koley, Goutam. 2008. "NO2 Detection Using Microcantilever Based Potentiometry." Sensors 8, no. 11: 7144-7156.