Research And Simulation Of The Thermal Insulation Property Of Porous Silicon Used In MEMS Micro Thermal Sensor

Recently, with the development of Micro-Electro-Mechanical System (MEMS) technology, porous silicon (PS) has got more and more attention due to its excellent mechanical and thermal isolation properties. In this paper, the application of PS as thermal isolation layer in MEMS micro thermal sensor is studied and simulated.A PS-based thermocouple micro thermal sensor was present in this paper. Theories about heat transfer, thermal conduct of film, finite element and thermocouple were studied first. An experiment was designed to testify thermal insulation property of PS that to deposit metal film like Pt on PS layer and get its power consume-temperature curves. The experiment which made a good preparation for micro sensor was simulated by ANSYS finite element analysis (FEA) software. The Loads of FEA were gotten by experiments and numerical calculation. The results of the simulations were close to the experiment because of the right FEA model and appropriate value of parameters (especially heat generation rate).A thermocouple micro thermal sensor was advanced, and the rudiment sensor was finished according to a certain experiment steps. Then the temperature of hot and cold ends was measured to test the feasibility of the sensor, and the heat of the hot end was gotten by electrified metal resistance instead of exposing to heat filed. The FEA models were built by using the method of plane, 3-dimension, volume offset and shell elements. Temperature distribution of the thermocouple micro thermal sensor was simulated by those methods. Heat generation and constant temperature field were respectively loaded on the hot end of the sensor in the simulation and the temperature of the cold end was close to the experiment data. Finally, the work of thermal design for PS-based thermocouple micro temperature sensor was carried out with the purpose of increasing the difference in temperature between hot and cold ends. The difference in temperature of final project was simulated by FEA static thermal analysis. 12℃temperature difference between hot and cold ends could be gotten when a constant temperature field of 100℃was loaded on hot end, while 30℃temperature difference in the first 12 seconds by using transient analysis.