The structure optimization of the carbon nanotube film cathode in the application of gas sensor

The carbon nanotube (CNT) film is used to fabricate the novel carbon nanotube film cathode (CNTFC) gas sensor, and the working voltage of the novel sensor at atmospheric pressure decreases to several hundred volts from the value of more than thousand volts of the traditional discharge gas sensor, however it is limited by that the space charge in the gap is very hard to diffuse after the breakdown of the gap. This makes the gap in conductance and next self-sustaining dark discharge impossible. To solve the problem, experimental study and simulation calculation were conducted to optimise the structure of CNTFC. Five CNTFCs with different structures were designed and the experiments were conducted to study discharge principle. It shows that the CNTFC could be chosen as a gas sensor, when it has the three characteristics of low working voltage, working at self-sustaining dark discharge state, and the space charge in the gap being easy to diffuse. The electric field distributions of the five CNTFCs were studied and calculated by using the finite element method. The results of the simulations and the experiments show that it is reasonable to use the CNTFC with the above three characteristics as a novel gas sensor. (c) 2006 Elsevier B.V. All rights reserved.