Electrohydrodynamic direct writing of high-resolution PVA hydrogels via thermally induced sol-gel transition

Polyvinyl alcohol (PVA)-based hydrogels have received a lot of attention due to their superior biocompatibility and versatile applications. However, the fabrication of structurally complex hydrogels at high resolutions (<100 μm) remains challenging, mainly due to limitations in traditional methods such as casting and extrusion-based 3D printing. This work proposes sol-gel electrohydrodynamic direct writing (SGEHD), a facile and low-cost platform integrating thermally induced sol-gel transition with electrohydrodynamic printing for the fabrication of high-resolution PVA hydrogels. By optimizing jet stability and controlling phase transition velocity, we achieved resolutions finer than 70 μm, surpassing the limitations of traditional PVA hydrogel fabrication techniques. This study also develops a method for the quality evaluation of deposited lines, and finally provides some examples of complex patterned gel processing with SGEHD to demonstrate the pattern fidelity of this technique.