A thermal bubble actuated micro nozzle-diffuser pump

A valve-less micropump using the principles of thermal bubble actuation and nozzle-diffuser flow regulation is successfully demonstrated. The pump consists of a meander-shaped resistive heater, a pair of nozzle-diffuser flow controllers, and a 1 mm in diameter, 50 /spl mu/m in depth pumping chamber. Liquid is actuated by periodically expanding and collapsing thermal bubbles via resistive heating and a net flow is induced by the nozzle-diffuser flow regulator. Both single-bubble and dual-bubble actuation modes have been investigated. In the single-bubble pumping mode, a maximum flow rate of 5 /spl mu/l/min is measured at the driving pulse of 10% duty cycle at 250 Hz under an average power consumption of 1 W. A similar flow rate of 4.5 /spl mu/l/min is measured in the dual-bubble pumping mode, at the driving pulse of 5% duty cycle at 400 Hz with 0.5 W of average power consumption. The highest measured pumping pressure is 377 Pascal at zero volume flow rate.