Concurrent Pulse-Echo and Through-Transmission Ultrasound Tracking with Multi-Frequency PMUTs

This paper introduces an application of piezoelectric micromachined ultrasonic transducers (PMUTs) designed for dual-functionality in ultrasound measurements. Utilizing a multi-frequency approach, this research validates the ability of PMUTs to simultaneously measure dynamic physical variables, such as blood vessel motion and fluid temperature changes. The PMUT array, incorporating transducers of various dimensions, transmits and receives signals across multiple frequencies, thereby effectively mitigating interference between pulse-echo and through-transmission techniques. Using a customized experimental setup that simulates the dynamic motion and temperature variations of a blood vessel model, this method improves the precision of simultaneous time-of-flight (ToF) and phase shift measurements. Experimental results demonstrate the system’s ability to track blood vessel model wall expansions from 5.1 mm to 5.6 mm while simultaneously monitoring the temperature of bio-mimicking fluid with a sensitivity of 9.7° per degree Celsius within the range of 35°C to 45°C.