3D Multifunctional Composites Based on Large-Area Stretchable Circuit with Thermoforming Technology

Fiber-reinforced polymer composites with integrated intelligence, such as sensors, actuators, and communication capabilities, are desirable as infrastructures for the next generation of internet of things. However, the shape mismatch between the 3D composites and a planar electronic circuit causes difficulties in integrating electronic circuit-based intelligences. Here, an easily scalable approach, by incorporating a large-area stretchable circuit with thermoforming technology, to fabricate 3D multifunctional composites is reported. The stretchable circuit is first fabricated on a rigid and planar carrier board, then transferred and sandwiched between thermoplastic composites through lamination processes. A thermoforming step shapes the sandwiched and planar structure by heating up the encapsulating polymers beyond their glass transition temperature and pushing them and the circuit against a mold. Using the proposed process, large-sized composites with integrated matrices of light-emitting diodes (LEDs) and capacitive sensors are successfully fabricated. A giant (with a size of 0.5 m x 1 m) seven-segment display is assembled using the fabricated composites with integrated LEDs and capacitive sensors to display 128 symbols. The results demonstrate the potential of the proposed approach as a facile, reproducible, and scalable process for creating 3D multifunctional composites.