A Quantification of Jet Speed and Nanofiber Deposition Rate in Near-Field Electrospinning Through Novel Image Processing

Abstract

Electrospinning, one of the most effective ways of producing nanofibers, has been applied in as many fields throughout its long history. Starting with far-field electrospinning (FFES) and advancing to the near-field, the application area has continued to expand, but lack of understanding of the exact jet speed and fiber deposition rate is a major obstacle to entry into precision micro- to nano-scale manufacturing. In this paper, we, for the first time, analyze and predict the jet velocity and deposition rate in near-field electrospinning (NFES) through novel image analysis process. Especially, analog image is converted into a digital image, and then, the area occupied by the deposited fiber is converted into a velocity, through which the accuracy of the proposed method is proved to be comparable to direct jet speed measurement. Finally, we verified the proposed method can be applied to various process conditions without performing delicate experiments. This research not only will broaden the understanding of jet speed and fiber deposition rate in NFES but also will be applicable to various areas including patterning of the sensor, a uniform arrangement of nanofibers, energy harvester, reinforcing of composite, and reproducing of artificial tissue.

Fiber Lithography: A Facile Lithography Platform Based on Electromagnetic Phase Modulation Using a Highly Birefringent Electrospun Fiber

“…Profiles also show that the half-cylindrical form of the fibers is maintained. The subset optical image shows lithographic exposure I out generated using fibers of various sizes . The variability in the brightness of individual lines indicates the relative retardation ability, , confirming the relationship between the t fiber and the I out .…”

“…The subset optical image shows lithographic exposure I out generated using fibers of various sizes. 29 The variability in the brightness of individual lines indicates the relative retardation ability, 43,47 confirming the relationship between the t fiber and the I out . Depending on the energy density required for the PR used in this work (150 mJ cm −2 ), the exposure time can be determined accordingly based on the UV irradiance (punching power).…”

“…NFES can generate a variety of programmable direct-write fiber patterns at microscale resolution. , Figure a shows a fiber pattern on an isotropic glass coverslip placed on a conductive substrate. The wafer is mounted on a motorized moving stage that operates in programmed paths.…”

“…To boost retardation exposure by increasing Δ n , we assembled a poly­(ethylene oxide) (PEO, 400 kg mol –1 , main chain) and a poly­(ethylene glycol) (PEG, 35 kg mol –1 , side chain), as shown in Figure g. First, we meticulously chose viscous PEO/PEG compounds as they have been extensively used in electrospinning ,, and we found that the PEO–PEG macromolecule plays a key role in exhibiting strong 1-D birefringence. The presence of the anisotropic cylindrical (helical) long chain when PEO is dissolved in water has been reported in multiple works. − When only PEO is used, however, the retardation intensity is not strong enough to perform lithography; significantly prolonged exposure time is required to achieve the required energy density of the PR.…”

Electric‐Field‐Assisted Single‐Step In Situ Fabrication and Focal Length Control of Polymeric Convex Lens on Flexible Substrate

“…In general, electrospinning is initiated when the electric field between the needle tip and the collector exceeds the threshold level, leading the electrostatic force acting between the ion inside the polymer solution and the conductive collector stronger than the surface tension of the polymer . However, when an excessive level of the electric field is formed between the tip and the collector, the unbalanced electric field creates a discontinuous polymer jet rather than forming a continuous fiber . By leveraging this interesting phenomenon, we apply this principle to the lens formation through accelerating and colliding polymer droplet onto the collector.…”