Engineering stimuli‐responsive shape‐morphing through high‐resolution 4D printing

Abstract 4D printing extends conventional additive manufacturing (AM) by enabling dynamic shape‐morphing structures that adapt to environmental stimuli. However, the spatial resolution of conventional 4D printing is often constrained by nozzle size, laser spot diameter, and material rheology, limiting its adoption in precision‐demanding engineering applications. High‐resolution 4D printing, integrating micro/nanoscale AM techniques with sub‐100 μm to sub‐100 nm structural resolution and stimuli‐responsive smart materials, has emerged as a promising solution to these challenges. Over the past decade, this approach has made significant strides in fields such as soft robotics, biomedical devices, flexible electronics, and microfluidic systems. This review summarizes recent progress in high‐resolution 4D printing, emphasizing key printing technologies such as digital light processing, PolyJet, projection micro‐stereolithography, two‐photon polymerization, and direct ink writing. A range of smart materials, including shape memory polymers, hydrogels, liquid crystal elastomers, and composite systems, are examined alongside their external stimuli, such as heat, light, humidity, and magnetic fields. Furthermore, the engineering applications enabled by high‐resolution 4D printing are discussed. Finally, the review highlights current challenges in material development, structural design, actuation speed, and scalable fabrication while offering future perspectives to stimulate further research and accelerate the industrial translation of high‐resolution 4D printing technologies.