Investigation on thickness of thin film gas sensor for high sensitivity gas sensor

Yap, Pei Yeuan (2022) Investigation on thickness of thin film gas sensor for high sensitivity gas sensor. Project Report. Universiti Teknikal Malaysia Melaka, Melaka, Malaysia. (Submitted)

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Abstract

VOC gas is a colourless and flammable gas. Hence, it is one of the main sources that causes combustion in high-temperature conditions. Besides, it is harmful to the health of living things. It will induce dizziness, headaches, vomiting, nose, eye, and throat irritation in the short term. In the long term, it will cause central nervous system damage, cancer, liver and kidney damage. As a result, a thin film gas sensor is used to detect the presence of VOC gases in the environment, although in a small region. A thin film gas sensor works on the premise of converting chemical quantities contained in gas into an electrical signal, such as current. The purpose of this project is to investigate the high sensitivity of thin film gas sensors at various thicknesses of the fabricated thin film. The substrates used are glass and Kapton film. There are several types of solutions used which consist of three different types of solvent (acetone, ethanol, and DI water) and three different concentrations of graphene power (0.01 g, 0.02 g, and 0.05 g of graphene power). The thickness of the thin film can be variable through different amounts of graphene power used in the solutions. All the prepared solutions are sonicated for 30 minutes to ensure they are well mixed. First, the electrode is screen-printed onto the substrates before being annealed at 150 degrees Celsius for 10 minutes. After that, a thin film is deposited on the substrate that contain electrode by applying the dropping process with one drop of solution and undergoing annealing at 150 degrees Celsius for 10 minutes. The resistance-containing thin film gas sensor will next be used to test the target VOC gases. The VOC gases used are acetone and ethanol. Finally, the results of the gas test are used to perform further research. The gas sensors that are fabricated on the Kapton film substrates with 0.01 g graphene and 10 g DI water have high sensitivity to acetone and ethanol, where sample D1a has a sensitivity of 3.24% and D1b has a sensitivity of 7.02%. Sample E5b has the shortest response time (1 s), whereas sample D-5b has the quickest response time (5 s) of all the samples. The majority of fabricated gas sensors are more sensitive to acetone than to ethanol gas.

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