Ultrafast Response of Electrothermal Actuator: Pulse-Step Relay Excitation Method

Electrothermal actuator, owing to its continuously adjustable output displacement and high compatibility with the silicon-based fabrication process, significantly promotes the progress in microsystems such as optical switch, safety and arm system, and laser ignition system. However, the response of electrothermal actuator is delayed since the slow Joule heating process of silicon structures, making it difficult to meet the demands for high-speed military and aerospace applications. The article aims to solve this long-existing bottleneck problem by optimizing the electric excitation for the electrothermal actuator. Based on the dynamic modeling of a coupling electrothermal actuator, a pulse-step relay excitation method is analytically developed to increase the response speed without bringing obvious overshoot. With the excitation of a pulse of 84.8 V and an on-coming step of 17 V, the coupling actuator reaches a displacement of 102.6 μm in 1 ms, 100 times faster than purely a step excitation of 17 V. The heat generation and dissipation mechanism of actuator under the pulse-step relay excitation are revealed to explain the essential of fast response. We believe this work is significant for providing electrothermal actuator-based microsystems with high response speeds, particularly where the electrothermal components limit overall system performance.