Flow rate self-sensing of a pump with double piezoelectric actuators

According to the method of segmenting electrode, the flow rate self-sensing of a conventional piezoelectric pump with the actuators of double diaphragms is presented in this paper. The novel pump is characterized by the simultaneous function of fluid transportation and the flow rate self-testing through only one piezoelectric element. The analysis indicates that direct and converse piezoelectric effect can be concurrently applied to obtain the simultaneous function through dividing the electrode of the piezoelectric element into driving unit and sensing unit. With two commercialized segmented-electrode piezoelectric diaphragms, a prototype pump is fabricated with the size of 65 mm x 40 mm x 12 mm and tested according to the frequency characteristics at a fixed driving voltage and the driving voltage characteristics at a fixed frequency. The results show that sensing voltages of diaphragms are increased or decreased with the change of the flow rate as a function of frequency. When the flow rate reaches the maximum value of 45.98 ml/min at 15 Hz, outlet/inlet sensing voltages also reach maximum values of 6.80 V-pp and 19.4 V-pp, respectively. It demonstrates that the pump itself could accurately reflect the optimal frequency through monitoring outlet/inlet sensing voltages. The testing results indicate the good linear relationship between outlet/inlet sensing voltages and the flow rate as a function of driving voltage. Therefore, both theoretical analysis and experiments have proved that flow rate self-sensing can be realized for the piezoelectric pumps with double actuators through segmenting their electrode. Moreover, if any electrode of double piezoelectric actuators is segmented, the pump can obtain the complete self-sensing function. (C) 2013 Elsevier Ltd. All rights reserved.