Regulation of Fiber Uniformity by High Voltage Power Supply in Electrospinning

Electrospinning technology, as an effective method for preparing fibers ranging from nanometers to microns, shows great application potential in many fields, such as tissue engineering, filtration materials, energy storage, etc. In the electrospinning process, the high voltage power supply plays a crucial role, and its regulation of fiber uniformity directly affects the performance and quality of the final product.
The basic principle of electrospinning is to use a high voltage electric field to form a Taylor cone at the nozzle of a polymer solution or melt. When the electric field force overcomes the liquid surface tension, a charged jet is ejected from the tip of the Taylor cone. During the flight of the jet, the solvent evaporates or the melt solidifies, and finally, fibers are formed on the receiving device. The electric field strength provided by the high voltage power supply is an important parameter that determines the jet behavior and fiber formation.
The stability of the electric field strength plays a decisive role in fiber uniformity. Unstable output of the high voltage power supply will cause fluctuations in the electric field strength, and then change the ejection speed and trajectory of the jet. When the electric field strength increases instantaneously, the jet may be ejected at an accelerated speed, resulting in a thinner fiber diameter; conversely, when the electric field strength weakens, the jet speed decreases, and the fiber diameter becomes thicker. This non uniformity of fiber diameter seriously affects the performance consistency of the product. To ensure fiber uniformity, the high voltage power supply needs to have a highly stable output characteristic. Advanced voltage stabilizing technologies, such as feedback control systems, are used to monitor and adjust the output voltage in real time, controlling the voltage fluctuation within a very small range. Thus, a stable electric field strength is maintained, ensuring the stable ejection of the jet and obtaining fibers with a uniform diameter.
In addition, the polarity switching ability of the high voltage power supply can also be used to regulate fiber uniformity. In some electrospinning processes, by periodically switching the polarity of the high voltage power supply, the distribution and movement direction of the surface charge of the jet can be changed. This dynamic change in charge distribution helps to reduce the bending and instability of the jet, making the fibers deposit more evenly on the receiving device. For example, under the action of an alternating polarity electric field, the jet is subjected to electric field forces in different directions at different time intervals, thus forming a more uniform distribution in space, avoiding excessive fiber aggregation or local sparseness, and significantly improving the overall uniformity of the fiber mat.
The output waveform of the high voltage power supply also has an impact on fiber uniformity. Traditional DC high voltage power supplies are widely used in electrospinning, but in recent years, it has been found that using a pulsed high voltage power supply with a specific waveform can improve the fiber formation process. The pulsed waveform can provide a high intensity electric field in a short time, promoting the thinning and stabilization of the jet. At the same time, the inter pulse period helps the solvent to volatilize fully or the melt to solidify better, reducing defects inside the fiber and further improving fiber uniformity. By optimizing parameters such as the frequency and duty cycle of the pulse, the morphology and uniformity of the fibers can be precisely regulated to meet the requirements of fiber performance in different application scenarios.
In conclusion, the high voltage power supply in electrospinning plays an irreplaceable role in regulating fiber uniformity by stabilizing the electric field strength, reasonably switching the polarity, and optimizing the output waveform. In depth research and precise control of various parameters of the high voltage power supply are of great significance for improving the quality of electrospun products and expanding their application fields.