Experimental investigations are performed to determine the influence of electrical excitation and geometrical parameters on the performance of piezoelectric valveless micropumps fabricated on printed circuit board substrates. Strain gauges and shunt resistor are used in conjunction with a data acquisition system to form an effective transducer, capable of providing magnitude and phase response information pertaining to fluid-structure interaction. Effect of conical diffuser geometry on the displacement response and pressure flow characteristics are studied. With suitable variations in the design of the diffuser element and input excitation parameters, the ability of the valveless micropump can be extended to include forward, reversed and bidirectional flow features. The characteristic signatures of single and two peaks in flowrate or pressure data are captured in the displacement phase response. System identification approach is proposed to model and predict the performance of valveless micropumps.

With constraints on size, cost, reliability, and performance for liquid-based cooling systems, the design of modular micropumps suitable for an integrated thermal management system still remains a challenge. In this paper, the effectiveness of a low-cost valveless micropump—heat exchanger on a printed circuit board is investigated for electronic cooling. Signal conditioning and control electronics are integrated with the fluidic components on the substrate to form a compact modular unit. Piezoelectric actuation and conical diffusers are utilized to generate pulsating flow through a minichannel heat sink. With ethanol as the working fluid, the tested pump reached a maximum flowrate and a pressure head of 2.4 ml/min and 743 Pa at an input voltage of 6 VDC. Suitability of the system for active real-time temperature control has been demonstrated at two input heater power levels of 1.45 and 2.5 W. A maximum reduction of 57 per cent in the average heat sink surface temperature could be achieved at a maximum power consumption of 150 mW by the micropump.