A flow rate on-line monitoring method for piezoelectric pump based on self-sensing circuit

This paper presents a new flow rate monitoring method for a piezoelectric micropump based on a self-sensing circuit. Utilizing the voltage generated by the secondary direct piezoelectric effect as the sensing voltage, a soft sensor of the piezoelectric actuator can be implemented onto the piezoelectric micropump. A bridge-type circuit is proposed as the self-sensing circuit, the piezoelectric micropump is fabricated with a circular piezoelectric actuator, the characteristics of the self-sensing voltage and the flow rate are experimentally investigated under different excitation voltages and frequencies. The results show that the method can accurately determine optimal frequency of the micropump (100 Hz, 280 Hz), and for a fixed frequency of 100 Hz and a voltage range of 50–180 V, the correlation between the self-sensing voltage and the flow rate is 0.9732. As a result, the method demonstrated in this paper allows precise monitoring of the flow rate of the piezoelectric micropump without using external sensors.