Phase-Sensitive Air Flow Measurement Using PMUTs

This paper presents an ultrasound-based airflow measurement using Piezoelectric Micromachined Ultrasonic Transducer (PMUT) transceivers. Two PMUTs are utilized, each with an active area of 0.28 mm 2 (chip size can be smaller than 1 mm × 1 mm), to measure the flow. The proposed flowmeter employs a phase-sensitive measurement technique that takes advantage of the phase difference between signals received upstream and downstream. The volumetric flow rate is directly proportional to the observed phase difference, and the sign of the phase difference indicates the direction of the flow. The performance of the developed flow meter is tested across a range of flow rates, from 0 to 52 Standard Liters per Minute (SLM), demonstrating high sensitivity and linearity. The small size and low operating voltage of the proposed flow meter make it particularly suitable for space and power limited applications.