Image processing of non-thermal glow discharge plasma during gas ionization process as a novel hydrogen detection system at parts per billion levels

Abstract

A new hydrogen (H2) detection system is introduced based on the image processing of non-thermal glow-discharge plasma of the ionization of H2 at parts per billion (ppb) levels based on gas ionization process under vacuum condition (∼8 torr). The system setup consists of a charge coupled device camera as detector. For this purpose, the blue component of the photographic image related to ionization-generated plasma is analyzed during applying a 853-V direct current potential to a two-electrode system including Al disk as cathode (diameter: 2.4 ± 0.1 mm) and multi-walled carbon nanotubes-modified disk (diameter: 6.5 ± 0.1 mm) as cathode with 700 ± 10 μm inter-electrode distance. Figures of merits of the fabricated sensor reveal two linear dynamic ranges between 5–36 and 36–180 ppb. Relative standard deviation of at most five replicate analyses during introduction of 90 ppb of H2 standard solution (in air as solvent) is found as 2.29%. Also, the detection limit was evaluated to ∼2.25 ppb. Except acetylene, no significant interfering effect is observed when introducing at least 1000 folds excess (mass/mass) of different foreign species. Reliability of the sensor is also evaluated via determination of H2 in different industrial gas samples.