Non-Contact Ultrasonic Flow Measurement for Small Pipes Based on AlN Piezoelectric Micromachined Ultrasonic Transducer Arrays

In this paper, we propose a non-contact ultrasonic liquid flowmeter based on AlN piezoelectric micromachined ultrasonic transducer (PMUT) arrays. Two 10 by 10 PMUT arrays with resonant frequency of 980 kHz in air are mounted outside of a pipe to measure liquid flow without contacting the liquid. An acoustic matching layer is designed to mitigate the loss of sound waves caused by sound reflection. Under excitation of continuous wave, the flow of the liquid can be determined via detecting the phase difference between transmitting and received signals. The measurement range of flow is 0.515 L/min similar to 3.40 L/min and the measurement error is less than 3%. Moreover, an interpolation method is proposed to reduce the signal sampling frequency without obviously affecting the measurement accuracy, which shows potential for further system integration. [2021-0033]

Automated summary

A non-contact ultrasonic liquid flowmeter based on AlN PMUT arrays is proposed in this paper, with an acoustic matching layer designed to mitigate sound reflection losses. The measurement range of flow is from 0.515 L/min to 3.40 L/min, with a measurement error of less than 3%. An interpolation method is also suggested to reduce signal sampling frequency without impacting measurement accuracy, indicating potential for further system integration.