Shock waves in an electrochemical microactuator

The explosive mode of operation of an electrochemical actuator is studied. In this mode of operation, we observe explosion of microbubbles containing the oxygen–hydrogen gas mixture that forms in the working chamber of the actuator during electrochemical water splitting by high-frequency pulses of alternating polarity. We demonstrate that shock wave emission occurs as a result of implosion of the void formed due to the microbubble explosion, rather than the explosion of the microbubble itself. Using the experimentally measured variation in the bubble wall velocity with the distance from the explosion center, we estimate the pressure amplitude at the shock front. The dynamic of microbubble collapse is established using time-resolved photography.