Design of Wearable Flexible Cross-Shaped Ultrasonic Transducer Array for Blood Pressure Estimation

Continuous blood pressure testing is an important method of assessing the cardiovascular health and blood circulation in daily life. A normal blood pressure range is also essential for human health. Existing common blood pressure measurement solutions are not suitable for long-term daily blood pressure monitoring purposes due to the large size of the devices and the discomfort they cause to the human body during the measurement process. In this study, a simple multilayer flexible piezoelectric composite ultrasonic transducer array is proposed that allows blood pressure measurement by continuous tracking of changes in the arterial vessel wall by ultrasonic waves. The single transducer vibrating element is designed and prepared by using a 1–3 piezoelectric material composite of PZT-5H and epoxy (EPOXY) resin. The 2-D array transducer designed in this work differs from other matrix transducers in that the use of the cross-shaped array can significantly increase the magnitude of the transmitted sound pressure at the center and the transducer array can also be simulated by the FPGA circuit board. The average frequency and −3-dB center beamwidth of the flexible piezoelectric array are 5 MHz and 1.12 mm, respectively, which determine the lateral resolution of the transducer array, as analyzed by simulation with field II software.