Study on the oil-filled isolated pressure sensor by a fluid-solid coupling method

Although MEMS (Micro Electro-Mechanical System) pressure sensor has been a considerably mature technology and successfully applied in various fields, Packaging is still a major challenge. For the application in harsh environment such as electrolysis, polarization, particulate contamination, corrosion, stiction and excessive heat dissipation, usually, the oil-filled isolated packaging strategy with a steel corrugated diaphragm would be used. Packaging effects of corrugated diaphragm characteristics and volume expansion of oil on sensor performance were studied by some researchers, while, previous researches simply focused on the corrugated plate or just considered the oil as an elastic material without the coupling effect between them. In this paper, a fluid-solid coupling model with the oil as a compressible fluid being simulated by the hydrostatic fluid element was established. The geometric features of corrugated diaphragm and the compression performance of oil were taken into consideration. The results show that more waves, smaller volume of oil would be preferred, and for a low pressure range, almost several kilopascal, the volume is the dominant factor for given specific oil. In order to verify the accuracy of the simulation method, an experiment was conducted, and a special-designed ceramic cubic can be attached around the pressure chip to decrease the oil volume. The output data of packaged modules were recorded under the temperature range from -40°C to 125°C, The trend of data is in good agreement with the prediction of simulation model. This simulating method can be an excellent tool for the research and development of similar packaged sensor.