Issue 28, 2022

Harnessing osmotic swelling stress for robust hydrogel actuators

Abstract

The volumetric expansion of hydrogels driven by osmotic swelling stress has enabled hydrogel actuators for myriad applications. However, most existing studies disregard optimizing the osmotic swelling stress for powerful actuation and simply utilize the osmotic swelling stress to trigger certain modes of actuation. In this work, we probe the osmotic swelling stress of hydrogels using polyacrylamide as a model system. We design and perform constrained swelling experiments to measure the osmotic swelling stresses at different levels of constraint and compare the results to the theoretical predictions based on the Flory–Huggins model. We optimize the osmotic swelling properties by tuning the constituents and structures of the hydrogel and achieve an enhancement of the magnitude of actuation stress from ∼180 kPa to ∼400 kPa. As a proof of concept, we demonstrate a robust hydrogel jack that can lift a weight 2000 times its own weight by harnessing the high osmotic swelling stress. The feasibility and limits of harnessing the osmotic swelling stress of hydrogels for actuation are discussed.

Graphical abstract: Harnessing osmotic swelling stress for robust hydrogel actuators

Article information

Article type
Communication
Submitted
07 may. 2022
Accepted
30 jun. 2022
First published
30 jun. 2022

Soft Matter, 2022,18, 5177-5184

Harnessing osmotic swelling stress for robust hydrogel actuators

X. He, J. Zhu and C. Yang, Soft Matter, 2022, 18, 5177 DOI: 10.1039/D2SM00591C

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