## 2 Experimental Setup
By implementing these high-temperature connecting terminals, the authors aimed to overcome the previous difficulties associated with connecting the printed circuits and connectors, leading to improved reliability and efficiency in the manufacturing process. To connect the PZT transducers and high-temperature connecting terminals, a small amount of conductive epoxy/hardener conductive agent was applied to the soldering points of the transducers and the high-temperature connecting terminals. Two thin layers of adhesive films were then placed in their designated positions for pre-bonding, followed by the placement of a PZT transducer on each layer. Blue tapes were used to secure the PZT transducers in place. Simultaneously, the high-temperature connecting terminals were positioned at the end of each printed circuit. Next, the Kapton(r) films, along with the connected PZT transducers and high-temperature connecting terminals, were subjected to a pre-curing process in an oven at 80 \({}^{\circ}\)C for 20 min. This pre-curing step aimed to prevent the conductive agents from flowing and causing short circuits during the subsequent vacuum and heating steps of the pre-bonding procedure. After pre-curing, the Kapton(r) films with the embedded PZT transducers were placed on a vacuum-heated table. A vacuum was applied, and the assembly was heated to 150 \({}^{\circ}\)C for 1 h to initiate the bonding process. The vacuum was maintained throughout the cooling process until the assembly reached room temperature. Once the pre-bonding was completed, the blue tapes used to secure the PZT transducers were removed from each transducer. This process of applying conductive agents, pre-bonding the PZT transducers with adhesive films, and performing vacuum bonding at elevated temperature ensured secure and reliable connections between the PZT transducers and the high-temperature connecting terminals. The removal of the blue tapes after the pre-bonding step allowed for further processing and testing of the embedded PZT transducers in subsequent experiments. The composite lay-up procedure when the Kapton preparation procedures were finished can be referred to in Figures 2 and 3. During the embedding, the resin films and prepared Kapton films with pre-bonded PZT transducers were placed in designated positions, as is shown in Figure 1b. The details of the whole embedding procedure can be referred to in the author's previous work [33]. When the fabrication was finished, two layers of adhesive films were placed between high-temperature connecting terminals and the surface of the composite laminates at the cut-out positions, and the release films were covered on top of these connecting terminals and fixed by blue tapes to prevent the resin from covering the surface of the connecting terminals. After the curing process, the composite panels were inspected using a handheld DolphiCam ultrasonic camera to assess the quality of the embedded PZT transducers. Figure 3: Schematic of cross-sectional part at cut-out position. Following the inspection, the edges of the composite panels were trimmed. Connectors (RS 514-4408) were then mounted on the designated edges and bonded using superglue (RS 473-445). Finally, soldering was employed to establish the connection between the circuits and connectors. Figure 4 illustrates an example of a composite panel with embedded PZT transducers after the trimming process. The panel depicted in the figure has a thickness of 2 mm. The introduction of the cut-out method allowed for the precise trimming of composite edges while preserving the integrity of the embedded circuits. This approach facilitated the subsequent mounting of connectors and the establishment of reliable connections through soldering. The resulting composite panel with embedded PZT transducers exhibited a streamlined and functional design, as demonstrated in Figure 4.