Assignment Of Carbon Nanotubes By Dielectrophoresis And Its Application In Gas Sensor

Carbon nanotube has porous microstructure and high surface area, so has strong absorption for some gas, which makes it a promising future in gas detection filed. Dielectrophoresis is used to purify, orientate, assign, screen carbon nanotube. Dielectrophoresis acts as a more and more important role in the manipulation of carbon nanotube.The technology of assign carbon nanotubes by dielectrophoresis and the gas sensing performance of the gas sensor fabricated by dielectrophoresis are researched in this paper. AC electric field is used to distribute carbon nanotubes on interdigitated gold electrodes, and the assignment effects are compared to the drop-casting method. It is discovered that carbon nanotubes can be assigned evenly between the gaps of the interdigitated gold electrodes under the AC electric fields. The frequency, voltage of the AC electric fields and the time are the influential factors of dielectrophoresis. Under the frequency of 10MHz, voltage of 10V and 5 minutes'dielectrophoresis, carbon nanotubes can achieved the best assignment on the interdigitated gold electrodes.The gas sensing performances of gas sensors fabricated by dielectrophoresis and drop-casting method were compared in the paper. Under the same test condition, the sensor fabricated by dielectrophoresis shows better stability and sensibility, shorter response time and recovery time than the sensor fabricated by drop-casting method. It has some relationship with the distribution density and the thickness of the carbon naotubes trapped on the interdigitated gold electrodes.Using dielectrophoresis can precisely quantify the amount of trapped nanomaterials by monitoring the amplitude, frequency of the AC voltage and the deposition time. Dielectrophoresis may be a promising technique for the application of fabricating carbon nanotubes-based sensors.