Fabrication of microscale hydrogels with tailored microstructures based on liquid bridge phenomenon

Microscale hydrogels (microgels) find widespread applications in various fields, such as drug delivery, tissue engineering, and biosensing. The shape of the microgels is a critical parameter that can significantly influence their function in these applications. Although various methods have been developed (e.g., micromolding, photolithography, microfluidics, and mechanical deformation method), it is still technically challenging to fabricate microgels with tailored microstructures. In this study, we have developed a simple and versatile method for preparing microgels by stretching hydrogel precursor droplets between two substrates to form a liquid bridge. Microgels with tailored microstructures (e.g., barrel-like, dumbbell-like, or funnel-like shapes) have been achieved through adjusting the distance between and the hydrophobicity of the two substrates. The developed method holds great potential to impact multiple fields, such as drug delivery, tissue engineering, and biosensing.