Near-field electrospinning for 2D and 3D structuring: Fundamentals, methods, and applications

Fabrication technologies based on electro-hydrodynamic processes have been extensively studied in the past decades. Near-field electrospinning (NFES), based on a stable cone-jet mode, is widely used to fabricate micro- and nano-scale fibrous structures for a variety of applications. However, previous reviews have given limited attention to the capabilities of NFES to fabricate 2D and 3D structures. This review introduces four key metrics of NFES capabilities, i.e., fidelity, resolution, response, and aspect ratio, to evaluate and summarize the advances of NFES technology. Specifically, the fundamental theories of the electro-hydrodynamic process are discussed to understand the effect of operating parameters on the metrics of NFES capabilities. Then, the methods to improve the metrics of NFES capabilities are summarized. Furthermore, the applications of NFES technology are reviewed by highlighting the functionality of each metric of the capabilities. Finally, the achievements and existing gaps in NFES technology are discussed to offer insights into future directions in the field.