Continuous and Non-Invasive Monitoring of Blood Pressure Based on Wearable Piezoelectric Micromachined Ultrasonic Transducers Array

Continuous monitoring of blood pressure (BP), one of the most critical vital signs, can provide direct and dynamic insight into cardiovascular status. Ultrasound has emerged as a widely-used approach for BP measurement due to its non-invasiveness and high penetration capability. This paper demonstrates a continuous, real-time, non-invasive, and wearable BP monitoring system based on an aluminum nitride (AlN) piezoelectric micromachined ultrasonic transducers (PMUTs) array. A $23\times 26$ PMUTs array, in size of $3\times 3$ mm2, is fabricated and packaged as a wearable device. The PMUTs array exhibits excellent acoustic directivity and penetration depth, allowing for the positioning of the radial artery and capture of the diameter waveform. Highly accurate monitoring of BP waveform is demonstrated, with precision and accuracy within 4.5 mmHg and 5 mmHg, respectively, meeting requirements of clinical use. This wearable device can maintain good and long-term contact with the skin, and provide stable monitoring of BP waveforms without any discomfort, even during the motion of hand. [2023-0085]