A low-g MEMS inertial switch with a novel radial electrode for uniform omnidirectional sensitivity

作者：Du Liqun^*; Li Yu; Zhao Jian; Wang Weitai; Zhao Wenjun; Zhao Wen; Zhu Heqing

来源：Sensors and Actuators A: Physical , 2018, 270: 214-222.

DOI：10.1016/j.sna.2017.12.068

• Low-g omnidirectional inertial switch
• Novel radial electrode
• Non-silicon surface micromachining
• Thickness compensation
• Anti-overload performance

A low-g MEMS inertial switch with uniform omnidirectional sensitivity is designed and fabricated for automotive airbags in this paper. The design objective acceleration of the switch is about 38g. By adopting the combination of Archimedes' spirals and a single circular proof mass as the mass-spring system, the switch can sense the applied accelerations from any radial directions in XOY plane. To obtain a good omnidirectional performance, a novel radial electrode with a spherical contact surface and novel serpentine springs is designed, and limitation blocks are beside it. The omnidirectional response of the switch is simulated and analyzed by ANSYS software. The simulated result indicates that the novel radial electrodes are conducive to achieve the uniform thresholds in all sensitive directions, and the switch can reach a reliable contact because of the novel serpentine spring. The switch is fabricated based on non silicon surface micromachining technology. To decrease the deviation of threshold acceleration induced by fabrication errors of crucial dimensions, a new method of "thickness compensation" is proposed. The fabricated prototypes were tested by the centrifuge device and dropping hammer. The switch can be triggered under an acceleration of about 40g from any directions in XOY plane and has an excellent anti-overload performance.

• 出版日期2018-2-1
• 单位大连理工大学