Research on the sensing performance calibration of omni-directional broadband interdigital transducer based on PVDF substrate

Structural health monitoring (SHM) is of vital importance to the detection of damage in large structures. Ultrasonic transducers used to excite and receive signals have become an important part of SHM. For the traditional PZT ultrasonic transducer, there are some shortcomings such as poor flexibility and designability. Due to the limitation of structure shape, the rectangular interdigital transducers, which are widely used in structural health monitoring, have difficulty in receiving signals in all directions and the frequency bandwidth is narrow and the detection efficiency is low. On this basis, it is proposed to use the flexible piezoelectric material PVDF as the substrate. Combined with the dispersion theory of aluminium plate and the design principle of IDT, an omni-directional flexible annular PVDF Interdigital Transducer (PVDF-IDT) is designed. The device is produced by 3D printing technology. The sensitivity, frequency response, orientation and other performances of the flexible annular PVDF-IDT are calibrated, which lays the foundation for its application in structural inspection.