Corona alternating current electrospinning: A combined approach for increasing the productivity of electrospinning (original) (raw)
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Pharmaceutics
Recently, the electrospinning (ES) process has been extensively studied due to its potential applications in various fields, particularly pharmaceutical and biomedical purposes. The production rate using typical ES technology is usually around 0.01–1 g/h, which is lower than pharmaceutical industry production requirements. Therefore, different companies have worked to develop electrospinning equipment, technological solutions, and electrospun materials into large-scale production. Different approaches have been explored to scale-up the production mainly by increasing the nanofiber jet through multiple needles, free-surface technologies, and hybrid methods that use an additional energy source. Among them, needleless and centrifugal methods have gained the most attention and applications. Besides, the production rate reached (450 g/h in some cases) makes these methods feasible in the pharmaceutical industry. The present study overviews and compares the most recent ES approaches succes...
Effective AC needleless and collectorless electrospinning for yarn production
Phys. Chem. Chem. Phys., 2014
Nanofibrous materials are essential components for a wide range of applications, particularly in the fields of medicine and material engineering. These include protective materials, sensors, cosmetics, hygiene, filtration and energy storage. The most widely used and researched technology in these fields is electrospinning. This method for producing fibers yields highly promising results thanks to its versatility and simplicity. Electrospinning is employed in multiple forms, among which needle and needleless direct current (DC) variants are the most distinctive. The former is based on the generation of just one single jet from a nozzle; hence this fabrication process is not very productive. The latter uses the destabilization of free liquid surfaces by means of an electric field, which enhances the throughput since it produces numerous jets, emitted from the surfaces of rollers, spheres, strings and spirals. However, although some progress in total producibility has been achieved, the efficiency of the DC method still remains relatively low. A further drawback of DC electrospinning is that both variants need a collector, which makes it difficult to combine DC electrospinning easily with other technologies due to the presence of the high field strength within the entire spinning zone. This paper describes our experiments with AC electrospinning. We show that alternating current (AC) electrospinning based on a needleless spinning-electrode provides a highly productive smoke-like aerogel composed of nanofibers. This aerogel rises rapidly from the electrode like a thin plume of smoke, without any need for a collector. Our work shows that AC needleless electrospinning gains its efficiency and collector-less feature thanks to the creation of a perpetually charge-changing virtual counter-electrode composed of the nanofibers emitted. High-speed camera recordings demonstrate the formation mechanism of the nanofibrous plume, which is wafted by an electric wind. This wind's velocity field is experimentally investigated. One potential use of AC needleless electrospinning is demonstrated here by spinning it into a yarn. † Electronic supplementary information (ESI) available: Supplementary information 1: a 'nanofibrous plume' emanating from the virtual collector, supplementary information 2: the nanofibrous plume, comprising recombined strands of nanofibers, moves away from the rod spinning-electrode, supplementary information 3: successive and repeated jet creations during AC electrospinning, supplementary information 4: a promising application of the nanofibrous plume in the production of nanofibrous yarns. See
Polish-Israeli Conference on Electrospinning and Tissue Engineering
AC electrospinning [1] is a method of forming a nanofibrous mass resulting from electro-hydrodynamic instabilities caused by the effect of an external altering electric field. Hydrodynamic instabilities are traditionally studied by Rayleigh's linear stability analysis. The periodically variable electric field intensity provides with the instability that is governed by a second-order linear differential equation for the time evolution of the capillary wave amplitude [2]. This equation has an oscillating parameter and is called Mathieu's equation. ∂2A(τ) ∂τ2 + (a − 2q cos 2τ)A(τ) = 0, where A(τ) is the wave amplitude, which argument is the dimensionless time τ [2]. Dimensionless parameters a and q encompass physico-chemical parameters of a spun polymeric solution (surface tension and mass density), parameters of the physical fields (amplitude, frequency of an electric field and acceleration of the gravitational field) and the wave number of the destabilized liquid surface. Acc...
Electrospinning: The Technique and Applications
Recent Developments in Nanofibers Research [Working Title]
Electrospinning is a useful and convenient method for producing ultrathin fibers. It has grabbed the scientific community’s interest due to its potential to produce fibers with various morphologies. Numerous efforts have been made by researchers and industrialists to improve the electrospinning setup and the associated techniques in order to regulate the morphology of the electrospun fibers for practical applications. Porous, hollow, helical, aligned, multilayer, core-shell, and multichannel fibers have been fabricated for different applications. This chapter aims to provide readers with a clear understanding of the electrospinning process: its principle, methodology, materials, and applications. The chapter begins with a brief introduction to the history of electrospinning, followed by a discussion of its principle and the basic components of electrospinning setup. The parameters that affect the electrospinning process such as operating parameters and the properties of the material...
Intech, 2023
Electrospinning is the process of producing fibers ranging from sub-micron to Nano-scale in diameter consistently and reproducibly. The Electrospinning consists of three main parts High voltage power source (up to 30 kV), Spinneret (such as a syringe, with a small diameter needle) and a conducting collector. The basic principle of electrospinning technique is that, when an electrically charged solution is feed through a small opening such as syringe pump, needle or a pipette tip then due to its charge the solution is drawn as a jet towards an oppositely charged conducting collector plate. The solvent evaporates gradually during jet travel towards the collecting plate and a charged solid fiber is laid to accumulate at the collector plate. The high voltage is connected to the end of a needle containing the liquid solution. The fiber collecting screen is expected to be conductive and it can either be a stationary plate or a rotating platform or substrate. The physics of electrospinning involves several key factors, including the electrostatic forces, surface tension and viscosity of the polymer solution.
Experimental Validation of Upward Electrospinning Process
ISRN Nanotechnology, 2011
An experimental investigation has been carried out to validate the concept of a new upward electrospinning process in producing polymer nanofibres. The role of gravitational force in this concept is reversed from the conventional downward electrospinning. This inversion results in more stretching of the fibre, less bead formation, and jet stability. An experimental setup is built inside a vacuum chamber in order to eliminate the ambient effects. The effect of various parameters such as applied voltage, needle-collector distance, solution concentration, flow rate, and needle size, on average fibre diameter and beads formation, was investigated using scanning electron microscopy (SEM).
The Design and Implementation of a Disk Electrospinning Device
Műszaki Tudományos Közlemények, 2020
The electrospinning procedure is a relatively simple and fast way of producing polymer fibers with diameters in the micrometer range. The one needle setup is commonly used due to its flexible design and effectiveness; however, this procedure has one major shortcoming; it has low productivity. The disk electrospinning design presented here combines the advantages of the corona and needleless electrospinning setups, namely the small solution surface area and high productivity. We used 33 wt% polyvinylpyrrolidone (PVP) solution to produce PVP fibers with the new design. The average fiber diameter of the produced PVP fibers was d = 446±116 nm, which is ~25 % larger compared to fibers produced with the one needle method.
Impact of Apparatus Orientation and Gravity in Electrospinning—A Review of Empirical Evidence
Polymers
Electrospinning is a versatile fibre fabrication method with applications from textile to tissue engineering. Despite the appearance that the influencing parameters of electrospinning are fully understood, the effect of setup orientation has not been thoroughly investigated. With current burgeoning interest in modified and specialised electrospinning apparatus, it is timely to review the impact of this seldom-considered parameter. Apparatus configuration plays a major role in the morphology of the final product. The primary difference between spinning setups is the degree to which the electrical force and gravitational force contribute. Since gravity is much lower in magnitude when compared with the electrostatic force, it is thought to have no significant effect on the spinning process. But the shape of the Taylor cone, jet trajectory, fibre diameter, fibre diameter distribution, and overall spinning efficiency are all influenced by it. In this review paper, we discuss all these de...
The use of an electrostatic lens to enhance the efficiency of the electrospinning process
Cell and Tissue Research, 2012
Electrospun scaffolds manufactured using conventional electrospinning configurations have an intrinsic thickness limitation, due to a charge build-up at the collector. To overcome this limitation, an electrostatic lens has been developed that, at the same relative rate of deposition, focuses the polymer jet onto a smaller area of the collector, resulting in the fabrication of thick scaffolds within a shorter period of time. We also observed that a longer deposition time (up to 13 h, without the intervention of the operator) could be achieved when the electrostatic lens was utilised, compared to 9-10 h with a conventional processing setup and also showed that fibre fusion was less likely to occur in the modified method. This had a significant impact on the mechanical properties, as the scaffolds obtained with the conventional process had a higher elastic modulus and ultimate stress and strain at short times. However, as the thickness of the scaffolds produced by the conventional electrospinning process increased, a 3-fold decrease in the mechanical properties was observed. This was in contrast to the modified method, which showed a continual increase in mechanical properties, with the properties of the scaffold finally having similar mechanical properties to the scaffolds obtained via the conventional process at longer times. This "focusing" device thus enabled the fabrication of thicker 3-dimensional electrospun scaffolds (of thicknesses up to 3.5 mm), representing an important step towards the production of scaffolds for tissue engineering large defect sites in a multitude of tissues.