Hydrogel-based strong and fast actuators by electroosmotic turgor pressure

Hydrogels are promising as materials for soft actuators because of qualities such as softness, transparency, and responsiveness to stimuli. However, weak and slow actuations remain challenging as a result of low modulus and osmosis-driven slow water diffusion, respectively. We used turgor pressure a...

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Bibliographic Details
Published in:Science (American Association for the Advancement of Science) 2022-04, Vol.376 (6590), p.301-307
Main Authors: Na, Hyeonuk, Kang, Yong-Woo, Park, Chang Seo, Jung, Sohyun, Kim, Ho-Young, Sun, Jeong-Yun
Format: Article
Language:English
Subjects:
Actuation
Actuators
Deformation effects
Electric fields
Electrolytic cells
Fatigue limit
Hydrogels
Semipermeable membranes
Turgor
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Summary:Hydrogels are promising as materials for soft actuators because of qualities such as softness, transparency, and responsiveness to stimuli. However, weak and slow actuations remain challenging as a result of low modulus and osmosis-driven slow water diffusion, respectively. We used turgor pressure and electroosmosis to realize a strong and fast hydrogel-based actuator. A turgor actuator fabricated with a gel confined by a selectively permeable membrane can retain a high osmotic pressure that drives gel swelling; thus, our actuator exerts large stress [0.73 megapascals (MPa) in 96 minutes (min)] with a 1.16 cubic centimeters of hydrogel. With the accelerated water transport caused by electroosmosis, the gel swells rapidly, enhancing the actuation speed (0.79 MPa in 9 min). Our strategies enable a soft hydrogel to break a brick and construct underwater structures within a few minutes.
ISSN:0036-8075
1095-9203
DOI:10.1126/science.abm7862