Development of Gas Sensor Based on Fractal Substrate Structures

Gas sensor plays a key role in many applications with sensitivity being a critical performance characteristic. Increasing the surface area of gas sensing material is one approach that can increase sensitivity. Fractal geometries, which have the large specific surface area and special fractal dimension, have previously been successfully used in the design of macrostructure and microstructure of gas sensors to improve their performance. In this article, the influence of geometrical structure of the substrate on the gas sensor performance has been investigated. Two fractal structures (Koch snowflake and Menger sponge) and one traditional structure (Cylinder) were fabricated by 3-D printing and coated in Ag-doped multiwalled carbon nanotube (Ag:MWCNT)-based sensing materials. The fabricated sensors were tested with nitrogen dioxide at different temperatures and humidity. Experimental results show that the sensitivity of gas sensors with fractal structures is increased more than twice that of those with traditional geometrical structures.