A thermal-bubble-actuated micronozzle-diffuser pump

• Published in: Journal of microelectromechanical systems 2002-12, Vol.11 (6), p.665-671
• Main Authors: Tsai, Jr-Hung, Lin, Liwei
• Format: Article
• Language: English
• Subjects: Actuation; Applied fluid mechanics; Applied sciences; Driving; Energy consumption; Exact sciences and technology; Flow rate; Fluid dynamics; Fluid flow measurement; Fluidics; Fundamental areas of phenomenology (including applications); Heat pumps; Heaters; Heating equipment; Mechanical engineering. Machine design; Microfluidics; Micropumps; Phase transitions; Physics; Power measurement; Precision engineering, watch making; Pressure measurement; Pulse measurements; Pumping; Temperature control; Volume measurement
• ISSN: 1057-7157; 1941-0158
• DOI: 10.1109/JMEMS.2002.802909

A thermal-bubble-actuated micropump by the principles of liquid/vapor phase transition and nozzle-diffuser flow regulation is successfully demonstrated. The micropump consists of a resistive heater, a pair of nozzle-diffuser flow controller and a 1 mm in diameter, 50 /spl mu/m in depth pumping chamber. The actuation 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 investigated. In the single-bubble pumping mode, a maximum flow rate of 5 /spl mu/l/min is measured when the driving pulse is 250 Hz at 10% duty cycle under an average power consumption of 1 W. A similar flow rate of 4.5 /spl mu/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 device, this valve-less micropump is used in a microfluidic system to enhance the fluid mixing by agitating the flows.