A MEMS-Based Ionization Gas Sensor Using Carbon Nanotubes

We demonstrate here the successful operation of an ionization gas sensor with a gap spacing $S$ of 2 or $\hbox{7}\pm \hbox{0.4}\ \mu\hbox{m}$ and using carbon nanotubes as the electrode material. The device is chip based and fabricated using a microelectromechanical system process. Application of a bias of 0.6–1.8 V $(S\approx\hbox{2}\ \mu\hbox{m})$ or 12–15 V $(S\approx\hbox{7}\ \mu\hbox{m})$ to the electrodes generates an electric field that is sufficient to field ionize He, $\hbox{CO}_{2}$ , and their mixtures in air with high sensitivity and selectivity. The approach is considered as effective for lowering the operation voltage of ionization gas sensors below 36 V (safety voltage criterion) and is significant for the development of the smart device in this field.