Direct‐Printing of Functional Nanofibers on 3D Surfaces Using Self‐Aligning Nanojet in Near‐Field Electrospinning

Abstract

This paper reports a high‐resolution, template‐free, and direct‐printing method of functional nanofiber on 3D surfaces using a self‐aligning nanojet (SA‐N) in near‐field electrospinning (NFES). In the lowest regime of NFES, the cone‐jet transition is induced by the surface current, which leads to a unique jetting configuration where the microscale Taylor cone (microcone) is formed on the surface of the spherical‐shape droplet. The microcone rapidly develops to the nanoscale jet where the tangential electric force dominates the kinematics of the charged jet. The spherical‐shape ejection boundary allows the jetting angle from 0° to ±90° in both convex and concave surfaces, enabling precise deposition of nanofiber regardless of the curvature of the 3D surfaces. Using SA‐N, precise printing of functional nanofiber is successfully demonstrated on various 3D geometries, including convex, concave, and inner surface of the 3D structure. The direct‐printing ability of nanofiber on 3D surfaces using SA‐N will be a promising strategy to utilize various functional polymers in flexible electronics, printed electronics, optics, and biomedical engineering.

Low‐Cost Fabrication Method for Thin, Flexible, and Transparent Touch Screen Sensors

“…[ 13 ] Due to the advantages, NFES has been drawn attention in recent studies. [ 14,18 ] However, on‐off control of jet stream has been one of its challenges. As a possible solution for this issue, masking layer could be used in order to avoid printing on unnecessary parts.…”

Printing Polymeric Convex Lenses to Boost the Sensitivity of a Graphene-Based UV Sensor

“…Since an ultrahigh molecular weight of PEO is used as a rich crystalline polymer solution for the NFES, the deposited fiber (width of 80–100 µm) served as a barricade mask that endures the oxygen plasma while etching the graphene. As a result, only the protected region covered by the spun fiber remained as a graphene photosensor channel [ 43 , 47 ], whereas the uncovered graphene was fully eliminated [ 48 ].…”

Rational Design of Advanced Triboelectric Materials for Energy Harvesting and Emerging Applications

“…Therefore, the preparation of 3D structured nanofibers using the NFE technique is increasing. [122] In addition, magnetic-fieldassisted electrospinning is applicable for complex structures and will likely be available for TENGs in the future because magnetic fields are easily precisely managed and the acquired fibers are more stable and could easy to transfer. [114,127] Another technology that produces large quantities of oriented fibers at low cost is centrifugal electrospinning, which has advantages in terms of production speed and yield.…”

“…For instance, NFE technology enables precise and controlled deposition of large numbers of fibers by significantly reducing the tip‐to‐collector distance and applied voltage (typically below 1 mm and 1000 V). [ 122 ] The technology has been suggested for enhancing the controllability of the fiber structure, internal crystallization, and device integration. [ 123 ] And the NFE technique has been increasingly implemented to design PVDF nanofibers with a high degree of orientation in TENGs and piezoelectric nanogenerators (PENGs).…”