Negative Voltage Effect on Electrospun Nanofiber Collection

Tyler Tankersley; Katherine Meinhold; Dr. Jennifer Robinson, PhD

Statement of Purpose: Electrospun nanofibers are an increasingly popular technique for tissue engineering due to their uniquely promising results in creating extracellular matrix (ECM)-like scaffolds. The fiber diameter of electrospun nanofibers mimics the tissue ECM macromolecules whose organization gives tissues their properties. This can be done by manipulating the key compositional, environment, and processing parameters including flow rate, distance from the collector, and voltage. To increase fibrous mesh collection and reduce waste, a negative voltage is commonly utilized at the collection point in conjunction with a standard positive voltage to create a stronger electric field between the needle tip and collector to focus the collection of fibers. Though commonly used for this purpose, the effects of negative voltage in conjunction with other processing parameters are not well characterized. As such, the objective of this study the hypothesis was to observe the collection with and without the addition of a negative voltage. Methods: To conduct this experiment 96 samples were spun at four different distances (15 cm, 20 cm, 25 cm, and 30 cm), four different positive voltages (12 kV, 15 kV, 18 kV, and 21 kV), and two different negative voltages (-2 kV and -5 kV). The samples were prepared as a mixture of PCL (143.143 g/mol) and chloroform (CHCl3) in a 20 w/v% solution. During collection, the positive voltage was applied at the needle tip, while the negative voltage was applied at the collector. The fiber diameter was imaged with a Phenom Pro Desktop scanning electron microscope and analyzed with ImageJ and DiameterJ. Results and Discussion: This study aims to concentrate the collection with the addition of negative voltage to reduce waste and allow for a larger sample product to be collected. Preliminary results indicate the collection was significantly more concentrated due to the negative voltage. The overall collection was more compact with increasing negative voltage as seen in Figure 1. In data not shown the overall fiber diameter for the control ranged from 6-9 um, -2kV diameter results were near 7-8um, and -5 kV ranged from 6-7.5 um. Conclusions: The addition of negative voltage to the electrospinning setup containing a positive voltage source yields an overall thicker and more concentrated collection with smaller fiber diameters. With the effects of these parameters known, experimenters may appropriately utilize specific negative voltage levels in their experiments for their desired outcome.