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Application of Fractal Geometry in Gas Sensor: A Review

Increasing the specific superficial area of gas sensing layer is a direction to improve the performance of sensors. Considering the special features, high specific superficial area of fractal geometry and the fractal properties of thin film in the deposition and growth progress, many studies have explored the relationship between fractal geometry and gas sensing characteristics of the sensors. In this paper, the application and development of fractal geometry in gas sensors are reviewed, the superiority of fractal geometry in the application of gas sensors, as well as the formation mechanism and influencing factors of fractal geometry are indicated. The advantages of fractal analysis in the characterization of film morphology and properties are also discussed. This review demonstrates that fractal geometry can be successfully used in the design of macro and micro structure of gas sensors to improve the performance of sensors. Films with appropriate fractal structure and best gas sensing performance can be obtained by controlling the deposition and parameters. 3D printing and MEMS technologies provide an implementation scheme to prepare sensors with fractal structure, such as electrodes and heater based on Hilbert curve and substrates based on Menger sponge.