Toward high-efficiency multi-material additive manufacturing: a two-step hybrid fabrication strategy

Multi-material objects enable the integration of diverse properties and functionalities through precise three-dimensional material arrangement. Recent research highlights additive manufacturing as a pioneering approach for fabricating these complex structures, offering unprecedented control over spatial material distribution. However, it faces significant limitations when producing multi-material objects in the traditional layer-by-layer manner, as the approach requires frequent material switching, making the process prohibitively time-consuming. In this work, we present a two-step multi-material additive manufacturing strategy which achieves the fabrication of multi-material objects by capillary-driving the materials into the pre-printed framework and curing them with external energy sources. This strategy fundamentally eliminates the frequent material switching that occurs in traditional multi-material printing, thereby significantly enhancing the manufacturing efficiency of multi-material objects. Moreover, this strategy accommodates materials previously incompatible with conventional 3D printing. Tailored mechanical properties of multi-material structures can be achieved by adjusting the porosity and position of the framework. By adding stimulus-responsive materials into the multi-material structure, the strategy also enables 4D printing. This strategy opens a new avenue for the development of multi-material additive manufacturing.