A Miniature, Broadband Focused PVDF-TrFE PMUT with Interface ASIC for High-Resolution IVUS Imaging

Intravascular ultrasound (IVUS) is widely used for high-resolution imaging of vascular walls and plaques. This work presents a focused 0.8-mm aperture IVUS piezoelectric micromachined ultrasonic transducers (PMUTs) based on a PVDF-TrFE piezoelectric copolymer, offering inherently broad bandwidth. A novel fabrication approach enabled spherical focusing on a freestanding PVDF-TrFE piezopolymer film which was fixed in shape using conductive and acoustically inert epoxy. The PMUT, integrated with a high-voltage-tolerant Analog Front End Application Specific Integrated Circuits (AFE-ASIC) on a 1.5 mm width tower-shaped PCB, achieved center frequencies of 40 MHz and greater with -6 dB bandwidth of up to 92%. Pulse-echo and beam scanning confirmed the achievement of axial resolution 20 μm and lateral resolution up to 75 μm at 2.4 mm focal depth. IVUS images acquired from stent phantoms and vascular tissue clearly resolved vessel layers and stent struts, demonstrating 5 mm penetration depth and the system's suitability for miniaturized, high-resolution IVUS applications.