Fabrication and Characterization of a Low-g Inertial Microswitch With Flexible Contact Point and Limit-Block Constraints

A novel contact-enhanced low-g inertial microswitch has been proposed and fabricated by surface micromachining technology in this paper. A novel segmental circle spring has been designed in the low-g inertial switch, which can decrease its stiffness compared with traditional semicircle spring. The dynamic response of the microswitch is simulated by ANSYS software, which has estimated its threshold acceleration and holding time. The vibrations of proof mass under the applied overload acceleration in the sensitive direction and the opposite direction are both simulated and analyzed, which demonstrates that the rebound of proof mass can be restrained effectively by the introduced limit blocks. The fabricated prototype has been tested by a dropping hammer system. The test results indicate that the threshold acceleration of fabricated inertial switch is ~25g with holding time ~650 μs. The overload acceleration of 80g, 120g have been applied on the fabricated prototype, and the test results indicate that the spurious trigger have been eliminated due to the limit blocks, which is in agreement with the simulation results. The acceleration of 100g is applied to the tested inertial microswitch with and without limit block in the opposite sensitive directions, respectively. The test result verifies the function of limit blocks.