A piezoelectric micropump with an integrated sensor based on space-division multiplexing

Abstract

This paper presents a new concept of a self-sensing piezoelectric micropump based on space-division multiplexing (SDM). By means of dividing the electrode of the piezoelectric diaphragm into two parts of driving unit and sensing unit, a sensor is integrated onto the piezoelectric micropump. A prototype micropump is fabricated from a finished segmented-electrode piezoelectric diaphragm in our laboratory. Through basic experiments using tap water as a working fluid, frequency and voltage characteristics of the flowrate, backpressure and sensing voltage are investigated. The frequency ranging 0–50Hz can be determined by the sensing voltage. When the maximal flowrate of 26.55ml/min is recorded at a driving frequency of 30Hz, the sensing voltage also achieves the maximum of 3.02Vp–p at a fixed excitation voltage of 150Vp–p. Experimental results indicate there is pretty good agreement between the sensing voltage and the flowrate as a function of excitation frequency or voltage. Moreover, it indicates that the piezoelectric micropump itself can accurately determine the optimal frequency through monitoring the sensing voltage with the method of SDM. In the backpressure-voltage experiment, along with the backpressure changing from 0 to the maximum of 7.1kPa at an excitation voltage of 210Vp–p, the sensing voltage also changes from 0 to the maximal voltage of 16.6Vp–p correspondingly at a fixed frequency of 30Hz. Experimental result also shows there is a linear relationship between the backpressure and the sensing voltage. Therefore, both theoretical analysis and experiments prove that the self-sensing method based on SDM could well reflect the variation law of the flowrate and backpressure for piezoelectric micropumps. The micropump design shows the feasibility of our current effort to realize the measurement of the output flow and backpressure without the additional testing instruments.