Surface acoustic wave sensor for low concentration mercury vapor detection
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Mercury (Hg) has always been a serious risk to the environment and human health. It is a very common contamination in petroleum industry, which may lower product quality, threaten operation safety and worker’s health even at a very low concentration. Consequently the detection of mercury is very necessary. Gold is widely used as sensing material of mercury because it has a specific affinity with mercury and the adsorption of mercury changes characteristics of gold such as resistivity and effective mass density. In this thesis, common methods for sensing mercury vapor concentration were summarized and a surface acoustic wave (SAW) sensor utilizing the adsorption of mercury on gold electrodes was proposed for 1 μg/m3 level low concentration mercury vapor detection. The working principle of SAW sensor was studied and finite element method models were built to optimize the sensor design. The influence of several physical structure parameters such as electrode width and pitch on the sensor sensitivity and response time were studied using the simulation model. According to the simulation results a prototype of SAW sensor was designed and fabricated. The sensor was then analyzed with network analyzer and tested with mercury vapor. Preliminary results were presented and analyzed in this work. Finally potential future work was proposed and discussed.