Design, modeling and simulation of a miniaturized gas ionization sensor: Optimization of the structure and operation

Abstract

Gas ionization sensor (GIS), made of two parallel plates, works on measuring the breakdown voltage of gases that is unique for each gas. The gas breakdown inside the gas chamber occurs due to the ionization of gas molecules by accelerated electron impacts. The acceleration of electrons is very depended on the effective electric field they experience. It is shown that metallic or semiconductor nanowires grown between the two plates improve the sensitivity of the device and breakdown voltages of the gases are considerably reduced. In this work we report the design, modeling, and simulation of a miniaturized GIS based on nanowires. We have developed simulating software based on an open source simulator XOOPIC. The simulation tool is based on combined Particle-In-Cell and Monte-Carlo-Collision approaches. The tool is developed to model and simulate the gas ionization sensor to detect various gases including greenhouse gases with optimized breakdown voltages.

An enhanced gas ionization sensor from Y-doped vertically aligned conductive ZnO nanorods

“…However, the observed time response was dominated by the filling and evacuating speed of our gas chamber rather than the true response time of the sensor. In fact, the theoretical simulation suggested that the ionisation process had the breakdown time scale of several nano seconds [48].…”

“…(2) gives higher discharge current density, J. E tip is the effective electrical field on the tip of the NRs, given by [48]: (3) where V is the voltage applied between electrodes and the d is the separation between the electrodes. The strength of E tip is, however, also significantly affected by the aspect ratio of the NRs determined by the ratio of their length to the radius.…”

Metal Decoration and Magnetic Field Effect on the Electrical Breakdown Voltage for ZnO Nanorods Gas Ionization Sensor

“…Electron impact ionization (EII) and field ionization (FI) processes were, respectively, proposed for nanomaterial configured as a cathode (Huang et al, 2009;Chivu and Kahrizi, 2013;Mahmood et al, 2013) and an anode (Longwitz et al, 2001;Huang et al, 2009). If the nanorod was biased as a cathode, electrons would be extracted form cathode and in turn be accelerated and impact with gas molecular.…”

“…If the nanorod was biased as a cathode, electrons would be extracted form cathode and in turn be accelerated and impact with gas molecular. Then the gas molecular would be ionized by electron bombardment (Longwitz et al, 2001;Huang et al, 2009;Chivu and Kahrizi, 2013;Mahmood et al, 2013). If the nanorod was biased as an anode, gases would be ionized near the surface of nanotips by strong field extraction of the most loosely bound electrons from gas molecules (Longwitz et al, 2001).…”

Miniaturized Gas Ionization Sensor Based on Field Enhancement Properties of Silicon Nanostructures

“…As applying this voltage is not practical, to scale down the breakdown voltage of the gases, 1D nanostructures could be applied as one of the electrodes. Enhanced local electric field (E loc ) is created at the tip of the nanostructures due to non-uniform distribution of charged carriers [27,28]. Field enhancement factor (β) characterizes the level of influence of the 1D nanostructures onto the electrostatic field distribution and can be defined as the field gain coefficient (β = E loc /E app ) [27].…”