Flexible ultrasonic transducer array with automatic phase calibration for arteriosclerosis detection

This study presents the development of a flexible ultrasonic transducer array with automatic phase calibration (FUT-APC) for high-resolution carotid artery imaging and continuous monitoring of vascular mechanical parameters. The transducer integrates element position sensing with real-time phase compensation, utilizing five flexible pressure sensors to reconstruct the curvature profile of the attached surface with a reconstruction error as low as 0.34  mm. The system maintains stable operation on complex curved surfaces, significantly improving imaging quality compared to conventional probes on bent or irregular geometries. A contact pressure visualization mechanism enables real-time monitoring of applied pressure, ensuring data consistency during long-term measurements. The FUT-APC has a center frequency of 4.6  MHz, a -6 dB focal width of 0.74  mm, and a bandwidth of 53 %. In phantom tests, the system achieved axial resolution better than 0.75  mm and lateral resolution better than 0.93  mm. In vivo testing successfully captured the dynamic diameter variations of the carotid arterial wall and, together with wall thickness measurements, enabled extraction of key mechanical parameters, including circumferential stress (83.1  kPa), strain (7.09 %), and static elastic modulus (1.17  MPa). The FUT-APC offers a wearable and accurate solution for early screening, risk assessment, and dynamic tracking of atherosclerosis.