Bendable Phased-Array Ultrasound Transducer for Imaging on Curved Surfaces

Flexible phased-array ultrasound transducers (PAUTs), promising for nondestructive testing in biomedical and industrial applications, are classified as stretchable or bendable. Stretchable PAUTs offer a superior solution for complex curved surfaces but face substantial variations in piezoelectric element pitches, particularly on surfaces with small radii, complicating position correction algorithms. Meanwhile, real-time measurement of the pitches remains a technical difficulty. In contrast, bendable PAUTs with limited variable pitches are currently more practical for engineering applications. This paper introduces an innovative bendable PAUT featuring a constant-pitch-preservation (CPP) design. It includes a flexible 12 × 12 piezo-composite element array bonded with silicone, allowing conformity to surfaces with varying curvatures while maintaining constant element pitches. This design enables accurate progressive time delays for precise ultrasound beam steering and focusing. Individual backing and matching blocks for each piezoelectric element enhance detection performance. Experimental results from pulse-echo inspections and sector scans validate its effectiveness in high-quality imaging.