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This work presents an automatic threshold shock-sensing trigger system that consists of a bi-stable triboelectric transducer and a levitation-based electrostatic mechanism. The bi-stable mechanism is sensitive to mechanical shocks and releases impact energy when the shock is strong enough. A triboelectric generator produces voltage when it receives a mechanical shock. The voltage is proportional to the mechanical shock. When the voltage exceed a certain level, the initially pulled-in microelectromechanical system (MEMS) switch is opened and can disconnect the current in a safety electronic system. The MEMS switch combines two mechanisms of gap-closing (parallel-plate electrodes) with electrostatic levitation (side electrodes) to provide bi-directional motions. The switch is initially closed from a small bias voltage on the gap-closing electrodes. The voltage from the bi-stable generator is connected to the side electrodes. When the shock goes beyond a threshold, the upward force caused by the side electrodes on the switch becomes strong enough to peel off the switch from the closed position. The threshold shock the system can detect is tunable using two control parameters. These two tuning parameters are the axial force on the bi-stable system (clamped-clamped beam) and the bias voltage on the MEMS switch (gap-closing electrodes). The actuation in macro-scale is thus directly connected to a sensor-switch mechanism in micro-scale. This chain makes an autonomous actuation and sensing stand-alone system that has potential application on air bag deployment devices and powerline protection systems. We provide a theoretical frame work of the entire system validated by experimental results.

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