Abstract

Hydrogels, hydrophilic polymer networks that retain large amounts of water, have revolutionized applications in wearable electronics, tissue engineering, wound healing, and drug delivery. 3D printing offers new opportunities for hydrogel development, thanks to its efficiency, rapid prototyping, and design flexibility. Here, we present a dynamic-fluid-assisted micro continuous liquid interface production system (DF-μCLIP), enabling the fabrication of intricate multi-material and functionally graded 3D structures with smooth material transitions, while maintaining μCLIP's high production speed. To facilitate seamless material switching, a specialized resin bath with carefully positioned fluidic channels on each side was developed to enable dynamic resin flow within the dead zone. Coupled with a customized serial material supply system, this system allows for smooth, on-the-fly switching of different materials in the resin bath without interrupting the continuous printing. This work highlights DF-μCLIP's ability to print hydrogels, such as ion-conductive self-healing (SH) hydrogels and electroactive hydrogels (EAH) for functional devices. For example, the SH hydrogel relies on interpenetrating polymer networks (IPN) formed by physically cross-linked poly(vinyl alcohol) combined with chemically/ionically cross-linked poly(acrylic acid) and ferric chloride. By carefully optimizing the resin’s composition, we balanced high-resolution printability and superb SH capability. On the other hand, EAH is particularly notable for its electroactuation properties, allowing it to change shape or size under an electric field. Our experiments demonstrate EAH's strength, flexibility, and responsiveness across various compositions and electric field strengths. The DF-μCLIP process successfully printed SH hydrogels and EAH into complex structures, like lattices, soft robotic grippers. These findings offer promising advancements in functional devices for diverse applications, such as soft robotics, wearable electronics, and regenerative medicine.

Bio

Dr. Xiangfan Chen is currently an assistant professor at the School of Manufacturing Systems and Networks in Arizona State University. He earned his PhD in Mechanical Engineering from Northwestern University in 2018 and his bachelor's degree in Mechanical Engineering from Shanghai Jiao Tong University. Dr. Chen’s research focuses on innovative metamaterials, photonics, as well as the development of advanced additive manufacturing technologies for functional devices, with applications in optics, soft robotics, wearable electronics, and regenerative medicine. His work has been published in prominent journals such as Advanced Materials, Research, Small, and Nano Letters, and has been recognized by research communities across manufacturing, materials science, and photonics. His research has received funding from National Science Foundation (NSF) Advanced Manufacturing and Future Manufacturing, the U.S.-Israel Binational Science Foundation (BSF), and other organizations. In 2024, Dr. Chen was honored with the Susan Smyth Outstanding Young Manufacturing Engineer Award from the Society of Manufacturing Engineers (SME).