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. © Springer-Verlag 2011.