Three-dimensional electronics (3-DE) is attracting much interest due to the increasing demands for seamless integration on curved surfaces. Nevertheless, it is challenging to develop 3-DE with high customizable conformity and stretchability. In a new report now published in Science Advances, Jungrak Choi and a research team in mechanical engineering, materials science and science and technology in South Korea presented a method to form three-dimensional electronics based on predistorted pattern generation and thermoforming. Using thermoplastic elastomer and liquid-metal-based conductive electrodes, they accomplished high thermoformability and stretchability during device fabrication and function. The new technology can facilitate a wide range of functionalities in wearable technologies.
Three-dimensional electronics have high customizability, 3D conformability and stretchability to form state-of-the-art stretchable electronics in response to the increasing demands to form curvilinear surfaces for wearable sensors. The process to directly develop 3-DE with high customizability, 3D conformability and stretchability on any complicated surface are in high demand. Among the many development methods, thermoforming is a manufacturing technique that uses thermoplastic deformation of a plastic film onto a 3D shaped mold with the advantages of low fabrication cost, large area scalability and quick prototyping. In this work, Choi et al. developed a method for 3-DE based on pre-distorted pattern generation and thermoforming abbreviated as PGT3DE with a thermoplastic elastomer and liquid metal-based conductive electrode. During the 3-DE fabrication process, the team applied a highly stretchable thermoplastic elastomer-based substrate such as styrene-ethylene-butylene-styrene (SEBS) and a stretchable conductive electrode such as eutectic gallium-indium-based liquid metal mixed with copper microparticles.
As proof of concept, the scientists designed a 3D circuit model and lit three LEDs on the 3D surface and noted its stretchability for flexible deformations, without electrical disconnection during the process. They also developed complicated shapes including an ear-shaped 3-DE. The team followed two key steps to form 3-DE based on the pre-distorted pattern generation and thermoforming (PGT3DE)