Fig. 5: Large-area flexible ultrasonic blood pressure sensor.
a Photograph of a large area of flexible ultrasonic blood pressure sensor while still on the support glass. See Fig. 1f for a photograph of the blood sensor placed in the neck. b Transmit transfer in Pa/V at the resonance frequency of 8.2 MHz of transmit elements, obtained using hydrophone measurements. c The pressure waveforms derived from the measured carotid phantom vessel diameters as a function of time. The diastolic pressure pd was taken from the reference blood pressure sensor, and the vessel stiffness α was fitted such that the obtained systolic peak pressure matched with the reference blood pressure. The red curve shows the blood pressure measured using a reference blood pressure meter. d Recorded in vivo ultrasound data of the carotid of a healthy volunteer of the optimally positioned array element.
