Architected Soft Matter and the 4th Dimension

Soft matter promises great potential for autonomous and intelligent engineering systems when precisely manufactured in specific architectures with programmed responses. Emerging pathway to create such dynamic systems involves additive manufacturing (often called 3D printing) of stimuli-responsive and programmable soft matter. This approach has been recently termed “4D printing”, with the 4th dimension being time. In this talk, additive manufacturing of various soft matter using projection micro-stereolithography (PµSL) is presented. PµSL is a micro 3D printing technique that turns light into a complex 3D structure by utilizing digital light processing (DLP) technology. Combining rapid, versatile, and scalable micro 3D printing technique with various functional soft matter, design principles and mechanics inspired by exquisite motions and morphologies in nature are physically realized. Micro-architectures that can transform, move, and even jump are demonstrated by programming of dynamic response of various responsive hydrogels. In addition, unprecedented access to micro- and nano-scale afforded by precision micro 3D printing allows for implementation of mechanics-driven design principles in micro-architectures, leading to mechanical properties far superior to those found in nature, such as ultra-low density and high stiffness. Furthermore, geometrically reconfigurable, functionally deployable, and mechanically tunable lightweight material is created through 4D printing with shape memory polymers. Also presented will be some of biomedical applications of 4D printing including a microneedle array with enhanced tissue adhesion and transformable culture tubes for rapid histological analysis of spheroids/organoids.