A Miniaturized Transit-Time Ultrasonic Flowmeter Using PMUTS for Low-Flow Measurement in Small-Diameter Channels

In this paper, we report a miniaturized transit-time ultrasonic flowmeter (TTUF) for low-flow measurement in small-diameter channels. The proposed TTUF contains two pieces of ScAlN-based piezoelectric micromachined ultrasonic transducers (PMUTs) and a π-type channel. The PMUTs contain 169 (13 × 13) square cells with the dimension of 2.8 × 2.8 mm ² , showing good transmitting sensitivity and receiving sensitivity at frequency of 1MHz in water. Experiment results show that the developed TTUF provides a wide range of flow measurements from 2 to 300 L/h with 1 % repeatability in the channel of 4 mm diameter, which is smaller than most of the reported ones.