Active Mixing Nozzle for Multi-Material and Multi-Scale 3D Printing

Multi-scale and multi-material 3D printing is new frontier in additive manufacturing. It has shown great potential to implement the simultaneous and full control for fabricated object including external geometry, internal architecture, functional surface, material composition and ratio as well as gradient distribution, feature size ranging from nano, micro, to marco-scale, embedded components and electro-circuit, etc. Furthermore, it has the ability to construct the heterogeneous and hierarchical structured object with tailored properties and multiple functionalities which cannot be achieved through the existing technologies. That paves the way and may result in great breakthrough in various applications, e.g., functional tissue and organ, functionally graded material/structure, wearable devices, soft robot, functionally embedded electronics, metamaterial, multi-functionality product, etc. However, very few of the established additive manufacturing processes have now the capability to implement the multi-material and multi-scale 3D printing. This paper presented a single nozzle-based multi-scale and multi-material 3D printing process by integrating the electrohydrodynamic jet (E-jet) printing and the active mixing multimaterial nozzle. The proposed AM technology has the capability to create multifunctional heterogeneously structured objects with control of the macro-scale external geometry and micro-scale internal structures as well as functional surface features, particularly, the potential to dynamically mix, grade and vary the ratios of different materials. An active mixing nozzle, as a core functional component of the 3D printer, is systematically investigated by combining with the theoretical analysis, numerical simulation and experimental verification. The study aims at exploring a feasible solution to implement the multi-scale and multi-material 3D printing at low cost.