A Flexible and Ultra-Thin Ultrasonic Sensor for Continuous Carotid Pulse Wave Monitoring

Pulse wave signals can reflect the status of the human cardiovascular system, and continuous pulse wave monitoring can guide disease diagnosis. While current ultrasonic devices can perform reliable diameter measurements, their rigid ultrasonic probes rely on precise control by the operator, which inevitably compresses the blood vessels and leads to erroneous recording. In this paper, a flexible piezoelectric ultrasonic sensor was proposed to continuously measure pulse waves by tracking the motion of the vessel wall. The flexible sensor is light (0.9 g), ultra-thin (600
$\mu\mathrm{m})$
, self-adhesive to the skin, and does not compress human tissue. On this basis, a measurement system was designed to monitor the carotid arteries of volunteers. The results showed that the flexible ultrasonic sensor could continuously measure the diameter pulse wave with high reliability.