A Thermal-Bubble-Actuated Micronozzle-Diffuser Pump

Abstract—A thermal-bubble-actuated micropump by the prin-ciples of liquid/vapor phase transition and nozzle-diffuser flow reg-ulation is successfully demonstrated. The micropump consists of a resistive heater, a pair of nozzle-diffuser flow controller and a 1 mm in diameter, 50 m in depth pumping chamber. The actua-tion mechanism comes from periodically nucleating and collapsing thermal bubbles. A net flow is generated from the nozzle to the diffuser by the nozzle-diffuser flow controller. Two heater designs, single-bubble and dual-bubble actuation mode, have been investi-gated. In the single-bubble pumping mode, a maximum flow rate of 5 l/min is measured when the driving pulse is 250 Hz at 10% duty cycle under an average power consumption of 1 W. A sim-ilar flow rate of 4.5 l/min is achieved in the dual-bubble pumping mode, at the driving pulse of 5 % duty cycle at 400 Hz with lower average power consumption, 0.5 W. The static pumping pressure is measured at a maximum value of 377 Pascal when the net volume flow rate is zero. As an application example in a microfluidic de-vice, this valve-less micropump is used in a microfluidic system to enhance the fluid mixing by agitating the flows. [742] Index Terms—Bubble, microfluidics, mixing, phase change, pump. I