Hydrogel-based soft actuators can operate in sensitive environments, bridging the gap of rigid machines interacting with soft matter. However, while stimuli-responsive hydrogels can undergo extreme reversible volume changes of up to ~90%, water transport in hydrogel actuators is in general limited by their poroelastic behavior. For poly(N-isopropylacrylamide) (PNIPAM) the actuation performance is even further compromised by the formation of a dense skin layer. Here we show, that incorporating a bioinspired microtube graphene network into a PNIPAM matrix with a total porosity of only 5.4 % dramatically enhances actuation dynamics by up to ~400 % and actuation stress by ~4000 % without sacrificing the mechanical stability, overcoming the water transport limitations. The graphene network provides both untethered light-controlled and electrically-powered actuation. We anticipate that the concept provides a versatile platform for enhancing the functionality of soft matter by combining responsive and two-dimensional materials, paving the way towards designing soft intelligent matter.
@article{arxiv.2303.13878,
title = {Overcoming water diffusion limitations in hydrogels via microtubular graphene networks for soft actuators},
author = {Margarethe Hauck and Lena M. Saure and Berit Zeller-Plumhoff and Sören Kaps and Jörg Hammel and Caprice Mohr and Lena Rieck and Ali Shaygan Nia and Xinliang Feng and Nicola M. Pugno and Rainer Adelung and Fabian Schütt},
journal= {arXiv preprint arXiv:2303.13878},
year = {2023}
}
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Shared First-authorship: Margarethe Hauck and Lena Marie Saure