Continuous Multi-Material Additive Manufacturing

Slice-based additive manufacturing has been intensively investigated due to its potential in complex 3-dimensional (3D) structure construction across various fields. Current researches focus on curing surface and resin formation regulation to realize continuous printing. However, multi-material construction necessitates vat switching, compromising construction continuity. Achieving simultaneous multi-material construction within a single layer and enabling continuous multi-material construction continue to pose substantial challenges. Here, we present a continuous multi-material additive manufacturing (CMAM) approach by integrating extruding multi-liquid phases into droplet-based 3D printing system. The multi-droplet-based multi-liquid reservoir enables both 2D patterning of multi-liquid materials and their real-time curing, along with continuous resin replenishment to achieve continuous multi-material 3D construction. Additionally, extrusion parameters (extrusion number, spatial distribution, and extrusion flow rates) are controllable layer by layer, leading to controllable muti-material 3D distribution. Interfacial fusion can be controlled by adjusting printing speed and resin viscosity, leading to enhanced mechanical adhesions of 2 materials without influencing interfacial boundary precision. Increasing extrusion number can realize multi-material 3D structure construction with controlled material distribution, which can be extended to 3D structure-based anti-counterfeiting and soft robotics, guaranteeing a highly efficient and sustainable approach to multi-material 3D fabrication.