Fabrication of Microscale Polymeric Wavy and Coiling Structures via Side-Electrode-Assisted Near-Field Electrospinning: Modeling and Experiments

It is challenging for the existing fabrication strategies to generate microscale wavy and coiling structures with low cost and high efficiency. In this work, we develop a novel and simple method that allows the fabrication of microscale wavy and coiling fiber arrays via near-field electrospinning (NFES). In addition to the main vertical electric potential for polymer jet generation, additional electrostatic signals are applied to the side-auxiliary electrodes to dynamically control the fiber deposition. Compared with traditional electrospinning based on the buckling instability or mechanical collector movement, the proposed method shows advantages in terms of the controllability, stability, accuracy, and minimal feature size. A theoretical model to describe the polymer jet behaviors has been proposed to simulate the fabrication process by considering the momentum balance of viscoelastic, charge repulsive, and electric forces. The model has been directly verified through the comparison with experimental results. The effects of different process parameters on the fiber deposition patterns are analyzed and discussed. The processing capability has been further demonstrated by fabricating two-dimensional wavy and coiling patterns as well as three-dimensional wavy structures with the radius of curvature less than 100 µm.