Heterogeneous Hydrogel Structures with Spatiotemporal Reconfigurability using Addressable and Tunable Voxels

Area of Science:

• Materials Science
• Robotics
• Polymer Chemistry

Background:

• Stimuli-responsive hydrogels offer integrated sensing and actuation, reducing device complexity.
• Uniform volume changes in traditional hydrogels limit applications requiring localized, dynamic deformations.
• Developing hydrogel systems for sophisticated robotic functions remains a significant challenge.

Purpose of the Study:

• To introduce soft voxel actuators (SVAs) for creating heterogeneous hydrogel structures with programmable spatiotemporal deformations.
• To demonstrate the fabrication of tunable SVAs using a one-step photopolymerization method.
• To showcase the potential of SVAs in enabling advanced hydrogel robotic applications.

Main Methods:

• SVAs fabricated via mixed-solvent photopolymerization utilizing poly(N-isopropylacrylamide) (PNIPAAm) cononsolvency.
• Tunable hydrogel properties (swelling ratio, rate, Young's modulus) achieved through material design and processing.
• Spatiotemporal deformations programmed by SVA arrangement and activated Joule heating.

Main Results:

• Heterogeneous hydrogel structures capable of programmable, localized, and time-varying deformations demonstrated.
• SVAs exhibit tunable mechanical and swelling properties, suitable for mass production.
• Functional robotic behaviors including object manipulation, obstacle avoidance, wave generation, and shape morphing achieved.

Conclusions:

• SVAs provide a versatile platform for creating complex, adaptive hydrogel structures.
• This innovation facilitates the development of tunable, untethered hydrogel robots with high degrees of freedom.
• Programmable hydrogel robots can operate effectively in unstructured and dynamic environments.