A Self-Adhesive Flexible Ultrawide-Bandwidth Triboelectric Ultrasonic Transducer for Non-Destructive Testing of Complex Industrial Structures

Ultrasonic inspection technology offers substantial potential for structural health monitoring of critical infrastructure in the petrochemical, energy, and other core industrial sectors. However, conventional ultrasonic transducers face three fundamental limitations, namely that rigid functional materials fail to conform to curved surfaces, their narrow frequency response hinders broadband detection, and dependence on couplants degrades signal stability in complex industrial scenarios. Herein, a flexible ultrawide-bandwidth triboelectric ultrasonic transducer (FTUT) featuring a nano-interlocked dual-diaphragm structure and self-adhesive silicone is proposed to address these challenges. The FTUT demonstrates a broadband response from 0.02 to 8.5 MHz, a high receiver sensitivity of 25 dB at 100 kHz, and excellent mechanical adaptability to surfaces with a minimum curvature radius of 10 mm. Leveraging its ultrawide bandwidth and flexibility, the FTUT enables in situ damage localization in thin-plate structures at low frequencies (20–200 kHz) and high-resolution detection of internal defects in thick-walled structures at high frequencies (0.2–8.5 MHz). Ultimately, this study establishes a next-generation sensing paradigm for high-precision, adaptive, and robust nondestructive testing in harsh, complex industrial environments.