A new design and manufacturing process for embedded Lamb waves interdigital transducers based on piezopolymer film

In this work a new technology for designing and manufacturing ultrasonic interdigital transducers (IDT) is presented. The piezoelectric material used is a metallised piezopolymer film made of polyvinylidene fluoride (PVDF) with electrode pattern obtained with a laser ablation process. Piezopolymer transducer prototypes are designed with wavelength of 8mm to operate with Lamb waves (symmetrical S0 mode). An experimental validation of the piezopolymer IDT design is demonstrated with a transmitter-receiver IDT pair embedded in a 3mm thick carbon fiber reinforced plastic (CFRP) composite laminate. Acoustical response and the electrical impedance have been calculated. These transducers are proposed for monitoring structural integrity of structures/components made of carbon epoxy composite laminates commonly used in spacecrafts, satellite and airplanes.