Design and Fabrication of 1-3 Piezoelectric Composite Material Air Coupled Ultrasonic Transducer

Air-coupled ultrasonic transducers play a crucial role in air-coupled in-situ defect detection techniques. This article focuses on the design, fabrication, and optimization of a high-sensitivity piezoelectric air-coupled ultrasonic transducer operating at a frequency of approximately 220 kHz. To ensure efficient acoustic impedance, a double matching layer structure was devised based on the fabricated piezoelectric material. Matching layer 1 was created using hollow glass microspheres filled with epoxy resin composite material. Interestingly, the addition of a diluent was found to enhance the vacuum degassing effect of matching layer 1. The sensitivity and working efficiency of the air-coupled ultrasonic transducer were further enhanced through the optimization of the matching layer thickness and the matching circuit. By independently optimizing the thickness of the double matching layers, the transducer's sensitivity and bandwidth were increased to -43 dB and 22.7%, respectively. Notably, the performance parameters of this transducer are comparable to, and in some aspects superior to, similar international products.