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Piezoelectric transducers of different extal diameters are designed and fabricated and incorporated into micropumps.Through finite element analysis,it is shown that the volume efficiency of the micropump reaches its maximum value for the first mode of vibration.The variation of maximum displacement with frequency is determined under free and forced vibration.Results demonstrate that this variation shows the same trend for different driving waves at the same driving voltage.The maximum displacement under forced vibration is less than that under free vibration.The displacement increases with decreasing distance from the center of the transducer.The maximum displacement is inversely proportional to the diameter of the transducer and proportional to the driving voltage under both free and forced vibrations.Finally,the micropump flow rate and pressure are measured and are found to manifest the same trend as the maximum displacement under the same driving conditions.For a piezoelectric transducer of 12 mm extal diameter,the maximum flow rate and pressure value are 150 μL/min and 346 Pa,respectively,under sine-wave driving at 100 Vpp driving voltage.