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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 mu m-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.

The graphene oxide (GO) microstructure, in terms of flake distribution, folding, and crumpling, in thin films affects properties such as electrical conductivity and optical transparency after GO reduction. A thin film can be tailored to the application if the microstructure of different deposition methods can be controlled. In this work, we compare the microstructures of GO coatings created through electrospray deposition (ESD) to randomly places flakes. The microstructure of ESD GO thin films can be altered through changes of the distance between the nozzle and the substrate. We developed a semi-automatic image analysis script that analyzes scanning electron microscopy images to find effects of GO stacking or agglomeration, without the risk of human bias. A low nozzle to substrate distance creates structures of flat GO flakes, but solvent flooding the samples cause drying patterns. A high nozzle to substrate distance folds and crumples GO flakes due to solvent evaporation, resulting in agglomerated GO on the substrate. Simulations are in agreement with a randomized placement of GO flakes for the dip coating process. For our setup, an ESD nozzle to sample distance of 2-4 mm produced coatings fairly close to a random distribution out of the ESD samples.