Liquid collector-assisted electrohydrodynamic printing of unrestricted-height architectures

Despite numerous efforts, electrohydrodynamic direct-writing still faces a significant challenge in constructing 3D architectures with considerable height. Herein, we present a liquid collector-assisted electrohydrodynamic (LCE) printing strategy to print architectures with unrestricted height. This method employs a liquid bath with an immersed descending platform instead of the traditional solid collector, enabling the ink to solidify at the liquid surface through solvent exchange while keeping the as-printed architectures always submerged in the liquid. Both theoretical analysis and experimental investigation reveal that optimizing the Z axis movement speed, based on the single-layer printing path length, printing speed, and flow rate, is pivotal to the execution of LCE printing. We demonstrate that LCE printing can continuously fabricate a honeycomb architecture until it reaches the depth limit of the currently used liquid bath, achieving a height-to-wall thickness ratio up to 1314, with a height of 67 mm and a wall thickness of 51 μm. The results indicate that LCE printing thoroughly addresses the limitation of printable height, making it a highly versatile, high-resolution 3D printing technique with potential applications in smart materials, energy devices, and biomedical engineering.