Flammable and noxious gas sensing using a microtripolar electrode sensor with diameter and chirality sorted single-walled carbon nanotubes

• Published in: Journal of micromechanics and microengineering 2013-08, Vol.23 (8), p.85022-9
• Main Authors: Cai, Shengbing, Duan, Zhe min, Zhang, Yong
• Format: Article
• Language: English
• Subjects: cross sensitivity; Detection; Electrodes; Exact sciences and technology; Field ionization; Flammable; gas sensing; Gas sensors; General equipment and techniques; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; partial discharge current; Physics; Sensor arrays; Sensors; Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing; Single wall carbon nanotubes; single-walled carbon nanotubes
• ISSN: 0960-1317; 1361-6439
• DOI: 10.1088/0960-1317/23/8/085022

We report on the utilization of densely packed (∼10 SWCNTs µm−1), well-aligned arrays of single-chirality single-walled carbon nanotubes (SWCNTs) as an effective thin-film for integration into a gas sensor with a microtripolar electrode, based on field ionization by dielectrophoretic assembly from a monodisperse SWCNTs solution obtained by polymer-mediated sorting. The sensor is characterized as a field ionization electrode with sorted SWCNTs acting as both the sensing material and transducer gas concentrated directly into an electrical signal, an extractor serving to improve electric field uniformity and a collector electrode completing the current path. The gas sensing properties toward flammable and noxious gases, such as CO and H2, were investigated at room temperature. Besides the high sensitivity, the as-fabricated sensor exhibited attractive behaviors in terms of both the detection limit and a fast response, suggesting that our sensor could be used to partly circumvent the low sensing selectivity, long recovery time or irreversibility and allow for a preferential identification of the selected flammable and noxious analytes. Interestingly, the excellent sensing behaviors of the sensors based on the field ionization effect derive directly from the combined effects of the high-quality, low defect SWCNTs arrays, which leads to a small device-to-device variation in the properties and the optimization of electrode fabrication, highlighting the sensor as an appealing candidate in view of nanotube electronics.