Experimental Study of Flow Rate Self-sensing with Piezoelectric Actuator for Portable Microfluidic Applications

Abstract

Flow rate sensing failure analysis and power saving are the most important and critical issues for portable piezoelectric-based micropump systems The proposed failure analysis methods can detect three types of failure according to the equivalent Butterworth-Van Dyke (BVD) model in the Lead Zirconate Titanate (PZT) actuator assembly stage They are PZT cracking uneven silver epoxy distribution and PZT inversion Failure analysis in the early stage of PZT actuator assembly helps to avoid making failure micropumps This failure analysis process can helps to improve manufacturing performance of micropumps Power saving is another important study for portable systems For saving the power design circuits with lower power consumption and recycling system power are most popular This article then proposes a charge recovery function for the peristaltic micropump driving circuit This dissertation presents a close-loop feedback flow rate self-sensing method for the piezoelectric-based peristaltic micropump system to measures liquid flow rate in the micropump The sensing could be integrated with a peristaltic micropump using piezoelectric actuators based on the time phase shift (TPS) method The presented sensing method can obtain the micro-flow rate within a micropump without any external flow sensors We fabricated a prototype piezoelectric peristaltic micropump with three chambers and three piezoelectric actuators in the laboratory The middle actuator works not only as an actuator for fluidic driving but also as a transducer for flow rate sensing An evaluation cycle is performed to ascertain the relationship between the flow rate and the phase shift of output signal responses from the transducer Experimental results demonstrate that the extreme small-scale flow rate in a piezoelectric peristaltic micropump can be measured by the proposed close-loop feedback method Experimental results show that the amplitude of the transducer output signal has an extremely linear relationship with the flow rate from 5 to 30 ul/sec The results are extended to propose a practical flow rate sensor the design of which can be realized easily in the piezoelectric peristaltic micropump system for sensorless responses that can detect the flow rate without any sensors or circuits The proposed TPS method is real-time integrated fast efficient and suitable for flow rate detection in piezoelectric peristaltic micropumps

Date of Award	2016 Jul 1
Original language	English
Supervisor	Ling-Sheng Jang (Supervisor)