Noninvasive Fluid Flowrate Detection Using Capacitive Micromachined Ultrasonic Transducers

Accurate detection of fluid flowrate in small pipes is essential for applications in medical diagnostics and aviation hydraulic system monitoring. However, traditional bulk PZT-based ultrasonic flowmeters are impractical in such contexts due to their bulky size and significant power requirements. This study introduces a novel approach utilizing capacitive micromachined ultrasonic transducers (CMUTs) for fluid flowrate measurement in small-diameter pipes (9 mm). Leveraging their compact size, enhanced electromechanical coupling coefficient, and lower voltage requirements, CMUTs offer a promising solution. The method relies on analyzing the time difference between upstream and downstream ultrasound wave propagation to determine the flowrate. The experiment results demonstrate the successful measurement of flowrates in small pipes, exhibiting exceptional linearity (correlation coefficient: 0.9935) between flow rate and time difference, with a high accuracy of 3%. These findings underscore the feasibility and reliability of employing CMUTs for ultrasonic flowrate detection.