Expanding Melt-Based Electrohydrodynamic Printing of Highly-Ordered Microfibrous Architectures to Cm-Height Via In Situ Charge Neutralization

It is a great challenge for melt-based electrohydrodynamic (EHD) printing to fabricate cm-height microfibrous scaffolds with uniform fiber diameter and highly-ordered architectures due to inherent charge-induced fiber repulsion and gradually-reduced electrical strength. Here, a novel approach is presented that involves incorporating the in situ charge neutralization technique into the melt-based EHD printing process. The addition of the charge elimination module can efficiently neutralize residual charges inside the EHD-printed microfibers and minimize fiber-fiber repulsion to ensure precise fiber deposition. Computational simulation indicates that the applied voltage should increase approximate to 0.15 kV as the printed structure height increases 1 mm to maintain a relatively constant electrical strength. The implementation of these two strategies in melt-based EHD printing successfully produces highly-ordered fibrous architectures with a maximum height of 10.01 +/- 0.18 mm and a uniform fiber diameter of 17.6 +/- 1.3 mu m. The resultant microfibrous architectures can guide large-area cellular alignment in 3D and function as supporting frames to reinforce mechanically-weak collagen hydrogel for engineering large-volume cellular constructs. To the authors' best knowledge, it is the first instance of directly producing cm-height, highly-ordered microfibrous architectures via melt-based EHD printing with in situ charge neutralization and constant electrical strength capabilities for tissue-engineering applications.