Electrospun nanofibers have numerous applications credit to the many advantages they possess including; small diameter, large surface-to-volume ratio, porosity and high flexibility. Such nanofibers are mainly produced through electrospinning. At present, electric field manipulation is one of the most efficient available techniques to precisely controlling an electrospinning jet. Currently, a plethora of literature exists on the effects of electric field manipulation on nanofiber deposition control. Nevertheless, much of this studies are limited exclusively to the control of a far-field electrospinning jet to deposit in one dimension or to suppress the chaotic whipping mode. To this regard, little has been done to control a near-field electrospinning jet for deposition of complex patterns using electric field manipulation.
Researchers led by Professor Ping Guo from the Chinese University of Hong Kong developed a novel design which entailed the addition of a moving sharp-pin electrode beneath the plane collector. Their main objective was for the sharp pin to be used to control the melt electrospinning jet for deposition of complex patterns by utilizing only the distribution of the electric field. Their research work is currently published in Journal of Manufacturing Processes.
The team begun their studies by charging the sharp pin electrode with a positive voltage and moving it so as to redistribute the electric field for jet trajectory control, while the plane collector was kept stationary. The team then studied the effects of focusing the electric field and the guiding effect of the jet trajectory due to the additional sharp-pin electrode. Additionally, parameters such as voltage, translation speed, and collection mechanism were extensively analyzed in order to provide a detailed empirical study of their effects on the fiber deposition control. Eventually, the collection mechanism between a conventional nearfield electrospinning setup and their proposed setup was compared so as to demonstrate the advantages of the proposed setup for better fiber deposition control.
The authors observed that, from the electric field focusing and jet trajectory guiding, the electric field lines were seen, not only to be convergent to the bottom pin electrode, but also possessed lateral components pointing to the intended jet trajectory. In addition, they noted that a general trend of a circular shape was being obtained from all nine cases following the trajectory of the moving pin electrode.
The Ping Guo and his team has presented an innovative design by adding a moving sharp-pin electrode beneath a stationary collector with the main aim being to control a near-field electrospinning jet by electric field manipulation. In this work, the effects of electric field focusing and jet trajectory guiding have been simulated and verified. From the observations made, it has been confirmed that the deposition accuracy is much improved compared with the conventional setup which utilizes a plane bottom electrode as a movable collector. Moreover, two-dimensional fiber patterns with various geometrical characteristics and small feature size have been successfully fabricated. In conclusion, the collected patterns are in good agreement with the moving trajectory of the pin electrode.
Xiangyu You, Chengcong Ye, Ping Guo. Electric field manipulation for deposition control in near-field Electrospinning. Journal of Manufacturing Processes volume 30 (2017) pages 431–438.
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