Abstract
Near-field electrospinning (NFES) is an additive manufacturing technique that allows for both high-resolution 3D structures and a wide variety of printed materials. Typically, a high electric field between a nozzle, the spinneret, and the substrate creates a μm-sized jet of a supplied liquid material. With mm distances between spinneret and sample, it is possible to have a fair control of the lateral placement of the deposited material. The placement is, however, distributed by various electrostatic phenomena, and this is one of the present challenges in developing NFES into a more versatile technique. In this paper, a higher degree of control in NFES placement was achieved through manipulation of the electric field direction, using an auxiliary steering electrode. The position of a polycaprolactone plastic jet was determined in real-time with a camera attached to a stereo microscope. The measured position was used to calculate an applied potential to the steering electrode to guide the plastic jet to the desired position. The placement accuracy was measured both at the substrate and during flight using the camera and microscope. The higher control was revealed through the deposition of plastic fibers in a pattern with decreasing separation, with and without the active steering electrode enabled. It is in the authors’ opinion that the fabrication of dense structures could be possible with further refinement of the technique.
Highlights
IntroductionNear-field electrospinning (NFES), known as electrohydrodynamic 3D-printing, is a recently developed method for direct-writing of micro- and nanofibers, with the potential of creating detailed structures in areas such as microelectronics
The use of an active steering electrode where a camera provides positional feedback of the PCL jet results in a significant increase in the placement accuracy of polymer fibers printed in high density patterns, estimated to roughly double the possible density of structures
The effect is more noticeable on the PCL jet in flight, where the control loop of the fiber placement operates but had an effect on the position further down on the substrate as well
Summary
Near-field electrospinning (NFES), known as electrohydrodynamic 3D-printing, is a recently developed method for direct-writing of micro- and nanofibers, with the potential of creating detailed structures in areas such as microelectronics. The technique allows for printing scaffold structures but not yet general solid 3D-structures. This work aims at evaluating the possibility to develop the NFES technique into a general additive manufacturing process, in analogy with the fused deposition modeling processes, by the use of an active electrostatic steering system. In the NFES process, a high voltage is applied between a spinneret, that is supplying liquid materials, and a substrate. The strong electric field forms a Taylor cone of the liquid material, and as the electrostatic forces overcome the surface tension, an electrohydrodynamic-jet (e-jet) of liquid material is continuously ejected towards the substrate.
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