Five-axis coordinated multi-material simultaneous 3D printing for geometrically conformal multi-material structures

The integration of functional devices with mechanical structures is crucial for developing compact and high-performance mechatronic systems. However, fabricating geometrically conformal multi-material structures and devices on curved surfaces remains a significant challenge. To address this challenge, we propose a five-axis coordinated multi-material simultaneous 3D printing method. It utilises a two-axis rotary print bed to maintain the printhead normal to the curved substrate and a customised printhead with three adjacent micro-holes to deposit three distinct materials simultaneously. 3D-printable dielectric elastomer and electrode inks with appropriate rheological properties for soft actuators were developed, and a computational fluid dynamics model was employed to study the multi-material simultaneous 3D printing process on curved substrates. The results demonstrate that this technology can successfully fabricate complex multi-material structures on both planar and curved substrates with excellent structural integrity and interfacial bonding. The process exhibits high controllability, enabling wide-range tuning of the overall filament width and independent control of individual material line widths. As a demonstration, ring-shaped multi-material soft actuators were fabricated and tested, exhibiting excellent flexibility and performance. Generally, this work presents an effective strategy for the integrated fabrication of conformal multi-material structures on curved substrates, facilitating the creation of advanced conformal functional devices.