Multimaterial Extrusion of Programmable Periodic Filament Structures Via Modularly Designed Extruder Heads

There is a growing interest in patterning multimaterial structures into one-dimensional, two-dimensional, and three-dimensional motifs with spatially programmable inner structures. Harnessing material extrusion technology with customizable extruder heads greatly expand the possibilities of 3D printing to generate diverse multimaterial structures. However, the current choices of extruder heads are still limited largely due to the complexity in the design and fabrication of high-resolution microfluidic channels for multimaterial ink extrusion. Here, we report a modular strategy in multimaterial extrusion to program periodic structures and material compositions in printed objects. Our modular design greatly simplifies the design and manufacturing of multimaterial extruder heads to rapidly print complex multilayered architectures. Moreover, different extruder head modules can be combined in series or in parallel and different filament morphology can be controlled by adjusting printing parameters such as flow rate and pressure. As exemplars, two immiscible materials with similar rheological properties but different mechanical properties are used for co-extrusion. The lamellar composite filaments and printed woodpile structures exhibit high toughness and superior energy-absorption capability, respectively. Our strategy provides new insights for the design of innovative filament structures for 3D printing and shows broad application prospects in tissue engineering, structural systems, optoelectronics and beyond.