A thermal bubble micro-actuator with induction heating

This paper presents a new type micro-actuator which is driven by the thermal bubble generated with induction heating. The water inside the actuator's chamber is heated by induction heating devices and changes from liquid phase to gas phase, generating vapor bubbles in the micro-actuator chamber. The volume of the bubble expands rapidly and the pressure in the chamber of the micro-actuator increases sharply. This pressure will push most of the water out of the chamber through the nozzle. Moreover, the reaction force of the water will cause the micro-actuator to move forward. Key parameters of the actuator are in micro-scale, such as the diameter of the inlet is 40 μm, the micro-heater core with an inner diameter of 100 μm and the nozzle with a diameter of 200 μm. A prototype of the micro-actuator is fabricated and experiments are conducted on the micro-actuator motion in water. The experiments show that the average velocity of the micro-actuator is about 0.14 mm/s when the power is at 0.535 W while the actuator is in contact with the bottom of the water container. Compared with the resistor thermal bubble micro-actuator, this micro-actuator has higher power bubble and larger reaction force. This micro-actuator can be used to drive micro-robotic in liquid and this new driving mode can also be applied in a variety of micro-fluid devices, such as the micro-jets, micro-switches and micro-pumps.