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To overcome longstanding fabrication bottlenecks in microscale actuation, this work establishes a manufacturing framework that decouples 3D colloidal geometry from chemical composition using soft lithography, swelling-assisted extraction, and sacrificial adhesive transfer. Across both liquid crystal elastomer and hydrogel chemistries, the authors fabricate high-fidelity chiral particles and high-aspect-ratio arrays that execute reversible, multi-stimuli thermal and optical shape morphing. When suspended, these programmed units exhibit coupled structural and optical dynamic interactions, providing an experimental testbed for emergent swarm behaviors in smart fluids.
Complex 3D colloidal microrobots can now be fabricated independently of material chemistry, unlocking shape-shifting micro-swarms capable of autonomous, stimulus-driven collective behavior.
Shape-programmable particles offer significant opportunities for microrobotic systems at the individual level and for hierarchical materials with emergent functionalities arising from collective particle behavior. However, fabricating shape-changing stimuli-responsive particles with complex three-dimensional geometries at colloidal length scales remains a major challenge. Here, we introduce a general fabrication framework that decouples particle geometry from material composition to produce free-standing three-dimensional colloidal particles with complex architectures. Our approach combines soft lithography, swelling-assisted extraction, and sacrificial adhesive transfer to fabricate particles with high geometric fidelity. We establish a predictive framework that defines the accessible design space for increasingly complex particle geometries. We further extend our framework to fabricate high-aspect-ratio pillar arrays with intricate three-dimensional architectures at colloidal length scales. To demonstrate material versatility, we fabricate particles from both liquid crystal elastomers and hydrogels. We show reversible shape-changing behavior of liquid crystal elastomer particles with cylindrical and chiral shapes under thermal and optical stimuli. In suspension, these particles display collective optical dynamic behavior arising from coupling between changes in the programmed liquid crystal organization within the particles and stimulus-induced geometric reconfiguration of the particles. Collectively, this work establishes a versatile platform for geometry-programmable colloidal particles with emergent collective functionalities, providing a route toward materials and fluids with dynamically programmable properties.