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Accidental falls are frequent and dangerous events for the elderly population, which can result into serious injury or fracture of bones especially hip bone injury or other joint fractures. There are several methods for detecting falls of elderly, such as camera-based, personal emergency response System (PERS), and wearable sensor-based. However, the camera-based method is limited by instrumented spaces and the PERS is suffer from inability to give an alarm after a fall. The wearable sensor based fall detection is not limited to instrumented spaces, moreover, it is easily to detect the falls through tracking the kinematic information about the monitored person. In this paper, a wearable Micro-electromechanical Systems (MEMS)-based sensors module is designed for fall detection including one three axis accelerometer, one three-axis gyroscope and one three-axis magnetometer. However, falls from activities of daily living (ADL) make it difficult to distinguish real falls from certain fall-like activities such as sitting down quickly and jumping. An approach is proposed using attitude angles to reduce false falls through tests of static postures and dynamic transitions. Meanwhile, the proposed method has real-time response and high computation efficien cy.

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 contam ination, 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 12S·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.

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