Real-Time Differential Ultrasonic Flow Sensing Enabled by PMUT Phased Array with a Novel V-Shaped Beam Pattern

Ultrasonic flow sensing offers significant advantages for non-invasive, adaptive monitoring in various scenarios. Traditional ultrasonic flowmeters are composed of paired transducers, which are used as TX/RX alternately to obtain the upstream and downstream flow information sequentially. Here, we demonstrated real-time ultrasonic gas flow sensing with a novel V-shaped beam pattern generated by a compact 3.6mm×3.6mm piezoelectric micromachined ultrasonic transducer (PMUT) phased array based on PZT thin film. By utilizing the grating lobe produced through optimized array pitch and sequential control, this 5-channel PMUT array breaks the conventional design limitations typically associated with grating lobes. The array generates a symmetric V-shaped beam pattern with dual main lobes measured at 27° and 153°, enabling real-time differential flow sensing in a single measurement (1000 times measurements in 1 second), and excellent linearity and robustness of measurement results under 1L/min-5L/min airflow.