Development of a self-sensing piezoelectric pump with a bimorph transducer

Abstract

This article presents a self-sensing piezoelectric pump with a bimorph transducer. The proposed method is able to realize the functions of fluid transportation and output flow and pressure self-testing simultaneously through only a single piezoelectric element. The simultaneous function is achieved through separating one lead zirconium titanate disk from the piezoelectric bimorph to detect the pumping flow or pressure in direct proportion to the bimorph deflection generated by the other actuated lead zirconium titanate disk. A prototype pump is fabricated with the size of 40 mm × 40 mm × 17 mm and tested according to the actuation frequency characteristics and voltage characteristics of the flow rate, backpressure, and sensing voltages. The testing results show that the sensing voltages are changed with the flow rate and backpressure as a function of frequency while either lead zirconium titanate disk of the bimorph act as the integrated sensor. It is found that when the pump with two distinct disks successively acting as the sensor separately achieves the maximum flow rates of 3.12 mL/min at 21 Hz and 2.93 mL/min at 22 Hz with a driving voltage of 150 V_pp, both corresponding sensing voltages also reach the maximum values of 6.88 and 6.72 V_pp, respectively. Driving voltage characteristics further indicate that both sensing voltages are linearly related to the pumping flow rate and backpressure. As a result, the sensing voltages can completely reflect the information of the flow rate and backpressure. Moreover, the pump with the piezoelectric bimorph transducer can obtain the complete self-sensing function no matter which disk of the bimorph is used as the integrated sensor.