Electro-Hydrodynamic Direct-Writing Technology toward Patterned Ultra-Thin Fibers: Advances, Materials and Applications

Fibers, having a large aspect ratio, have become an essential material in human life since the dawn of civilization. Lots of efforts have been made in controlling the fine structure and architecture of fibers for diverse applications. However, great technological challenges remain on patterning fibers with diameters down to tens of nanometers into the desired structure through conventional methods. Electrohydrodynamic direct-writing (EHDDW) technology shows great potential in depositing the highly aligned micro/nanofibers in a noncontact, direct, and controllable manner which can achieve a real-time adjustment and individually accurate control even on flexible, curved substrates. In this review, beginning with a brief introduction to the history of EHDDW, we first discuss its basic principle and typical apparatus. We continue with a highlight of its rise over the past decades as a powerful technology for the production of nanofibers with versatile compositions and structures. Afterward, we summarize the applications of such controlled nanofibers, including their uses as smart wearables, energy harvesting/conversion/storage components, and biomedical scaffolds. In the end, we discuss the opportunities and the development directions for this promising area. (C) 2020 Elsevier Ltd. All rights reserved.