Monolayer heterojunction interactive hydrogels for high-freedom 4D shape reconfiguration by two-photon polymerization

Area of Science:

• Biomimetic engineering
• Materials science
• Robotics

Background:

• Mimicking natural systems inspires advancements in 4D hydrogel robotics and interactive devices.
• Current limitations in miniaturized, biocompatible 4D hydrogels hinder progress.
• Controllable shape reconfiguration is crucial for advanced applications.

Purpose of the Study:

• To spatiotemporally program micro/nano hydrogels for high-freedom shape reconfiguration.
• To overcome limitations in current 4D hydrogel technologies.
• To develop novel biomimetic hydrogel-based micro/nano robotics.

Main Methods:

• Utilized a heterojunction geometric strategy with femtosecond laser direct writing (fsLDW).
• Employed polyethylene incorporated N-isopropylacrylamide as programmable interactive materials.
• Fabricated hydrogel monolayer nanowires as fundamental building blocks.

Main Results:

• Demonstrated dynamic chiral torsion, site-specific mutation, and anisotropic deformation.
• Achieved selective structural coloration and spontaneous self-repairing in hydrogel nanowires.
• Constructed micro/nano grippers, 2D-to-3D transforming structures, and photonic crystals.

Conclusions:

• Hydrogel-materialized monolayer nanowires offer high reconfiguration freedom and mechanical performance.
• Biomimetic fsLDW enables precise spatiotemporal construction of micro/nano hydrogel devices.
• Geometry-modulable hydrogels pave the way for reproducible micro-robotics and lab-on-chip devices.