Junya Suehiro et al 2003 J. Phys. D: Appl. Phys. 36 L109 doi:10.1088/0022-3727/36/21/L01
Junya Suehiro1, Guangbin Zhou and Masanori Hara
Show affiliationsThis paper describes a new method for fabricating a gas sensor composed of multi-wall carbon nanotubes (MWCNTs) using dielectrophoresis (DEP). MWCNTs dispersed in ethanol were trapped and enriched in an interdigitated microelectrode gap under the action of a positive DEP force that drove the MWCNTs to a higher electric field region. During the trapping of MWCNTs, the electrode impedance varied as the number of MWCNTs bridging the electrode gap increased. After the DEP process, the ethanol was evaporated and the microelectrode retaining the MWCNTs was exposed to ammonia (NH3) gas while the electrode impedance was monitored. It was found that the electrode impedance was altered by ppm-levels of ammonia at room temperature. The ammonia exposure decreased the sensor conductance, while the capacitance increased. The sensor showed a reversible response with a time constant of a few minutes. The conductance change was proportional to ammonia concentration below 10 ppm and then gradually saturated at higher concentrations. Effects of the number of trapped MWCNTs on sensor response were also discussed.
82.80.Fk Electrochemical methods
Issue 21 (7 November 2003)
Received 8 August 2003
Published 15 October 2003
Junya Suehiro et al 2003 J. Phys. D: Appl. Phys. 36 L109
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