Light-responsive intelligent microstructures constructed via dual 3D architectures

Light-responsive intelligent micromachines hold great promise in soft robotics owing to their localized actuation and flexible remote control. Nevertheless, it remains challenging to realize light-driven micromechanical structures featuring low actuation thresholds, rapid responses, and complex deformation capabilities. Here, a single-material-based dual-3D (3D programmable design and 3D deformation) printing strategy based on two-photon polymerization direct laser writing (TPP-DLW) technology is proposed for fabricating light-responsive smart actuators. The polydopamine nanoparticles are doped into the hydrogel as a photothermal conversion functional material. By virtue of the dual-3D printing strategy, precise control over voxel distribution and density at the nanoscale can be achieved to provide asymmetric crosslinking networks. Employing this approach, we successfully developed micro-crab claws that imitate the swinging and closing motions of actual crab appendages and humanoid micromachines capable of multi-degree-of-freedom "dancing" movements. The proposed strategy offers broad application potential in diverse areas.