Preliminary study on verification of using a gap sensing element to measure gas concentration

Abstract

To realize the gas concentration and non-contact gap measurements by using a single sensing element, the gas-sensitive material is designed into a coil-shaped structure, and the coil-shaped component made of SnO2 by sputtering is used as an example to verify the aforementioned idea. The experimental results demonstrate that, at the non-contact gap of 10 mm, the electrical resistance/impedance amplitude/impedance angle of the coil-shaped component decreases/decreases/increases with the increase of ethanol vapor concentration range from 0 ppm to 5000 ppm. The logarithmic value of gas concentration versus the sensitivity of electrical resistance/impedance amplitude/impedance angle curve exhibits the nonlinear error of 8.57%/2.92%/1.61%, and the sensitivity of electrical resistance/impedance amplitude/impedance angle peaks at 111.36%/9.72%/5.26% under 5000 ppm ethanol vapor concentration. The average value of the absolute gap sensitivity of impedance amplitude/angle towards the non-contact gap (from 10 mm to 5–10 mm) attains the maximum of 44.55 ± 5.87KΩ·mm−1/0.3050 ± 0.0568°·mm−1 at the ethanol vapor concentration of 0 ppm/5000 ppm. Based on the above results, a method is proposed for decoupling the change of the electrical resistance and impedance induced by the gas concentration and non-contact gap, and this paper verifies preliminarily the feasibility of using the coil-shaped component to measure the non-contact gap and gas concentration simultaneously.