Multi-material 3D fabrication at the nanoscale has been a long-sought goal in additive manufacturing, with great potential for the direct construction of functional micro/nanosystems rather than just arbitrary 3D structures. To achieve this goal, researchers have introduced several nanoscale 3D printing principles, explored various multi-material switching and combination strategies, and demonstrated their potential applications in 3D integrated circuits, optoelectronics, biological devices, micro/nanorobots, etc. Although some progress has been made, it is still at the primary stage, and a serious breakthrough is needed to directly construct functional micro/nano systems. In this perspective, the development, current status and prospects of multi-material 3D nanoprinting are presented. We envision that this 3D printing will unlock innovative solutions and make significant contributions to various technologies and industries in the near future.

Electrohydrodynamic (EHD) jet printing represents a novel micro/nano-scale additive manufacturing process that utilises a high-voltage induced electric field between the nozzle and the substrate to print micro/nanoscale structures. EHD printing is particularly advantageous for the fabrication on flexible or non-flat substrates and of large aspect ratio micro/nanostructures and composite multi-material structures. Despite this, EHD printing has yet to be fully industrialised due to its low throughput, which is primarily caused by the limitations of serial additive printing technology. The parallel multi-nozzle array-based process has become the most promising option for EHD printing to achieve large-scale printing by increasing the number of nozzles to realise multichannel parallel printing. This paper reviews the recent development of multi-nozzle EHD printing technology, analyses jet motion with multi-nozzle, explains the origins of the electric field crosstalk effect under multi-nozzle and discusses several widely used methods for overcoming it. This work also summarises the impact of different process parameters on multi-nozzle EHD printing and describes the current manufacturing process using multi-nozzle as well as the method by which they can be realised independently. In addition, it presents an additional significant utilisation of multi-nozzle printing aside from enhancing single-nozzle production efficiency, which is the production of composite phase change materials through multi-nozzle. Finally, the future direction of multi-nozzle EHD printing development is discussed and envisioned.