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Journal of Sensors
Volume 2015, Article ID 260382, 8 pages
http://dx.doi.org/10.1155/2015/260382
Research Article

Gas Sensors Based on Locally Heated Multiwall Carbon Nanotubes Decorated with Metal Nanoparticles

1Centro de Componentes Semicondutores (CCS), Universidade Estadual de Campinas (UNICAMP), CP 6061, Rua João Pandia Calógeras 90, 13083-870 Campinas, SP, Brazil
2Departamento de Física, Universidade Federal do Ceará, P.O. Box 6030, 60455-900 Fortaleza, CE, Brazil
3Divisão de Tecnologias Tridimensionais (DT3D), Centro de Tecnologia da Informação Renato Archer, Rodovia D. Pedro I Km 143.6, 13069-901 Campinas, SP, Brazil
4Laboratório de Microfabricação, Centro Nacional de Pesquisa em Energia e Materiais (CNPEM), Rua Giuseppe Máximo Scolfaro 10.000, Pólo II de Alta Tecnologia, 13083-970 Campinas, SP, Brazil

Received 28 September 2014; Accepted 6 February 2015

Academic Editor: Xiao-Miao Feng

Copyright © 2015 R. Savu et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

We report the design and fabrication of microreactors and sensors based on metal nanoparticle-decorated carbon nanotubes. Titanium adhesion layers and gold films were sputtered onto Si/SiO2 substrates for obtaining the electrical contacts. The gold layers were electrochemically thickened until 1 m and the electrodes were patterned using photolithography and wet chemical etching. Before the dielectrophoretic deposition of the nanotubes, a gap 1 m wide and 5 m deep was milled in the middle of the metallic line by focused ion beam, allowing the fabrication of sensors based on suspended nanotubes bridging the electrodes. Subsequently, the sputtering technique was used for decorating the nanotubes with metallic nanoparticles. In order to test the as-obtained sensors, microreactors (100 L volume) were machined from a single Kovar piece, being equipped with electrical connections and 1/4′′ Swagelok-compatible gas inlet and outlets for controlling the atmosphere in the testing chamber. The sensors, electrically connected to the contact pins by wire-bonding, were tested in the 10−5 to 10−2 W working power interval using oxygen as target gas. The small chamber volume allowed the measurement of fast characteristic times (response/recovery), with the sensors showing good sensitivity.