Miniature and Wireless Ultrasonic Imaging System for Wearable Human Carotid Artery Health Monitoring

This paper presents a miniature and wireless ultrasonic imaging system based on a high-frequency piezoelectric micromachined ultrasonic transducer (PMUT) array. The high fill-factor rectangular PMUT array with multimodal fusion operates at a center frequency of 11 MHz with bandwidth 7.5 MHz and transmitting sensitivity 8.25 kPa/V at 5 mm from the surface, achieving a great figure of merit (FOM) of 61.9 MHz×kPa/V. The 64-channel array, fabricated using a cavity silicon on insulator (CSOI) substrate, shows less than 4% frequency variation, ensuring excellent consistency. The superior electrical-mechanical-acoustic coupling efficiency and broad bandwidth provide a great margin for signal-to-noise ratio loss, a challenge of miniature systems due to compact circuit size and simplified signal processing. The miniature and wireless ultrasonic imaging system was developed and tested with the human carotid artery, achieving detailed imaging of arterial walls and lumen. The small size and high performance make it promising for wearable monitoring with continuous and non-invasive assessment, which is essential for early detection of atherosclerotic changes and cardiovascular health management.