Dispersion and dielectrophoresis alignment of carbon nanotube for application of NO₂ gas sensor

Gas sensor or chemical sensors are attracting tremendous interest because of their widespread application in industry, environmental monitoring, space exploration, biomedicines and pharmaceutics. Gas sensor with high sensitivity and selectivity are required for leakage detection of explosive gases such as hydrogen and for real time detection of toxic and pathogenic gases in industries. Also there is strong demand for the ability to monitor and control our ambient environment especially with the increasing concern of global warming. Researchers from NASA are seeking the use of high performance gas sensor for identification of atmospheric components of various planets. Therefore the gas sensor based on nanomaterial such as carbon nanotube (CNT's) nanowire, nanofibre and nanoparticle have been investigated widely. Upon exposure to certain gases the change in properties of CNTs can be detected by various methods. As a result a CNTs based gas sensing system and theoretical analysis of gas adsorption and collision effect on nanotube have been the subject of intense research. In this paper, we have proposed a gas sensor which will be made up of carbon nanotube using dielectrophoresis (DEP) technique. This technique requires a non-uniform electric field and a dielectric particle (in our case it is SWNTS) on which the dielectrophoresis force will act. This will align the CNT between the electrodes, which will act as channel for conduction and the same channel will be exposed to toxic gases for the sensing phenomen. For the alignment of individual SWCNTS it need to be debundled first which will be achieved through the dispersion of SWCNTs in the solvent like N, N Dimethyl formamide (N, N DMF) to achieve a homogeneous dispersion the SWCNTs will be first functionalized from acid mixture of H₂SO₄.HNO₃.