Osmosis-Driven Large-Scale Actuation for Shape-Shifting Mechanisms
Elio Challita, Tony G. Chen, Rachel S. Zoll, Michelle C. Yuen, Robert J. Wood
Abstract
Osmosis-driven actuation offers a promising strategy for developing untethered, environmentally responsive soft and shape shifting mechanisms and robots. In this work, we explore the use of superabsorbent polymer (SAP) pellets as large-scale, shape-morphing actuators. Upon exposure to water, these approximately 2mm diameter spherical pellets undergo a dramatic volumetric expansion, up to 300 times their initial volume, generating actuation forces of approximately 10 N under constrained conditions. We further demonstrate reversible cyclic actuation via controlled swelling-deswelling using ethanol-water solutions. Finally, we integrate these systems into a shape-morphing wheel design to enable adaptive locomotion that passively transitions between terrestrial and aquatic environments. Our findings demonstrate SAP-based osmotic actuators as an environmentally-driven solution for soft robotics, and shape-shifting soft hybrid mechanisms.
BibTeX
@inproceedings{iros2025_osmosisdrivenlar,
title = {Osmosis-Driven Large-Scale Actuation for Shape-Shifting Mechanisms},
author = {Elio Challita and Tony G. Chen and Rachel S. Zoll and Michelle C. Yuen and Robert J. Wood},
booktitle = {IROS 2025},
year = {2025}
}