MEMS-based microelectrode system incorporating carbon nanotubes for ionization gas sensing

A novel microelectrode system incorporating CNTs with some short gap sizes (S = 6, 7, 8, 10, 12 μm) that can generate non-thermal plasmas without high voltage operation and additional ionization sources is introduced in this paper. The characteristic current–voltage (I–V) and current–time (I–t) in the discharge process exhibit some self-protecting behaviors from the thermal plasma generation, which is similar to the dielectric barrier discharges. The threshold effects, which are sensitive to the gap size and gas species, definitely exist in the micro discharges in the electrode with a micrometer gap size and one-dimensional materials. As gas sensors that can monitor gas species and concentration at the atmospheric pressure, the sensitivity, selectivity and stability issues are tested. The results show the significantly improved performance, including the safe operation voltage (around 36 V), higher accuracy and selectivity, over the conventional device operated by the same principle. Furthermore, the device is facile to be realized using the microelectromechanical system (MEMS) fabrication technology, thanks to its chip-based nature. Additionally, the underlying physics are also under scrutiny in this paper in light of the fluid model of the discharge.