Micro-bubble actuator in JMM highlights list

The publication Bubble nucleation in an explosive micro-bubble actuator by Dennis van den Broek and Miko Elwenspoek is featuring in the Journal of MicroMechanics and Microengineering highlights collection of 2008.

Explosive evaporation occurs when a thin layer of liquid reaches a temperature close to the critical temperature in a very short time. At these temperatures spontaneous nucleation takes place. The nucleated bubbles instantly coalesce forming a vapour film followed by rapid growth due to the pressure impulse. In this publication we take a closer look at the bubble nucleation. The moment of bubble nucleation was determined by both stroboscopic imaging and resistance thermometry. Two nucleation regimes could be distinguished. Several different heater designs were investigated under heat fluxes of hundreds of W mm². A close correspondence between current density in the heater and point of nucleation was found. This results in design rules for effective heaters.