Fabricating and controlling PCL electrospun microfibers using filament feeding melt electrospinning technique

Abstract

The process of melt electrospinning has received noteworthy attention due to its ability to fabricate micro scaled polymer fibers. Recently, a melt electrospinning process has been attracting attention for biomedical applications, in particular with scaffold fabrication for tissue engineering. In order to enhance cell attachment and proliferation on scaffolds, it is important to control fiber diameters to create an environment to which cells can attach, grow, and proliferate with ease. However, because electrospinning is a process with many parameters, it is particularly difficult to precisely control the diameter of the resulting fibers. Also, polymer powders or pellets melted in nozzles are typically used for melt electrospinning. However, a filament feeding melt electrospinning process has not been yet been implemented. In this study, we developed a melt electrospinning device which can feed PCL (Polycaprolactone, Mw: 80 000 g mol−1) filaments for advanced electrospun fiber diameter control. The PCL filaments were first fabricated by a small scale micro-compounder and then fed into the melting chamber of the electrospinning device. The system was then heated to a desired temperature, and the melt was extruded through a nozzle. The potential difference between the nozzle and counter electrode then drew down the PCL extrudate, creating fine microfibers. Temperature was controlled and monitored via a customized temperature control system. In order to control the dispensing of the PCL filaments, a customized control algorithm using NI (National Instruments) LabVIEW was used. In order to actively cool PCL filaments, a miniature computer fan was attached on the side of the melting chamber so that the filaments would not buckle. This paper reveals the investigation of significant process parameters that influence fiber diameters and their optimization. For instance, applied voltages, distances between the nozzle and a counter electrode, processing temperatures, and polymer resin flowrates were varied. We also studied and summarized the effect of duty cycle—a ratio of forward and backward motions of the filament within a cycle time—for advanced fiber diameter control. Moreover, the relationship between a flow rate and a duty cycle and their influences on a fiber diameter were studied.

Solution electrospinning with a pulsed electric field

“…For another, the duty cycle was the measurement of the working hours, which was the function time of the electric field force. When the duty cycle increased, it was equal to the time of the electric field force consuming more in a cycle time, so the jet became longer because of the stretching of the electric field force, and the fiber diameter decreased . However, for the concave curve of the diameter distribution, an optimal duty cycle might have existed, and at this point, the jet had the best electric field force, which the range of jet whipped minimally.…”

Customization of Electrospinning for Tissue Engineering

“…The wire is pushed through the nozzle by a step motor while the controlled heater warms up the nozzle. 3D printer heads can be used in combination with the electrospinning chamber and such custom made devices for production of fibrous scaffolds have been recently investigated [13,14,15].…”

“…Fabrication of complex 3D structures also by combining several materials is especially important in tissue engineering [11] even though 3D printing is still under development regarding available materials [12]. Additive biomanufacturing is an important area of research pertaining to tissue regeneration [13], control of fiber diameter and micromechanics [14] or distribution and size of pores within fabricated scaffolds for implantable medical devices [15]. Furthermore, combination of 3D printing and electrospinning has been investigated in fabrication of vascular grafts [16], complex functionalized three-dimensional structures [17] and three-dimensional micro-patterns within 3D structures [18].…”

Commercializing Electrospun Scaffolds For Pluripotent Stem Cell-Based Tissue Engineering Applications

“…The technique spins highly charged polymer solutions into nanofibers or microfibers. In addition to the voltage field used to charge the polymer, other parameters play a key role in this process, including collection distance between the extruded polymer and the collector, the method of fiber collection, needle size used for extrusion and some other material-related parameters like molecular weight, solution concentration, viscosity and the type of solvent used to dissolve polymer or the melting point of the polymer [46][47][48][49][50]. A wide variety of polymers have been electrospun into scaffolds, including both natural and synthetic materials [51].…”

“…These nanofiber scaffolds have been combined with PSCs to engineer a variety of tissues, including neural, cardiac, and cartilage. The Willerth lab has done extensive work designing and fabricating such multifunctional scaffolds for promoting the neuronal differentiation of PSCs [47,59,69,70]. For instance, Mohtaram et al showed that encapsulation of retinoic acid inside engineered nanofibers with different topographies enhanced the neuronal differentiation of mouse iPSCs while guiding the outgrowth of neurites from these cells along the scaffold topography [55].…”