High-performance electrified hydrogel actuators based on wrinkled nanomembrane electrodes for untethered insect-scale soft aquabots

Jongkuk Ko, Changhwan Kim, Dongjin Kim, Yongkwon Song, Seokmin Lee, Bongjun Yeom, June Huh, Seungyong Han, Daeshik Kang, Je Sung Koh, Jinhan Cho

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27 Citations (Scopus)


Hydrogels have diverse chemical properties and can exhibit reversibly large mechanical deformations in response to external stimuli; these characteristics suggest that hydrogels are promising materials for soft robots. However, reported actuators based on hydrogels generally suffer from slow response speed and/or poor controllability due to intrinsic material limitations and electrode fabrication technologies. Here, we report a hydrogel actuator that operates at low voltages (<3 volts) with high performance (strain > 50%, energy density > 7 × 105 joules per cubic meter, and power density > 3 × 104 watts per cubic meter), surpassing existing hydrogel actuators and other types of electroactive soft actuators. The enhanced performance of our actuator is due to the formation of wrinkled nanomembrane electrodes that exhibit high conductivity and excellent mechanical deformation through capillary-assisted assembly of metal nanoparticles and deswellinginduced wrinkled structures. By applying an electric potential through the wrinkled nanomembrane electrodes that sandwich the hydrogel, we were able to trigger a reversible and substantial electroosmotic water flow inside a hydrogel film, which drove the controlled swelling of the hydrogel. The high energy efficiency and power density of our wrinkled nanomembrane electrode-induced actuator enabled the fabrication of an untethered insect-scale aquabot integrated with an on-board control unit demonstrating maneuverability with fast locomotion speed (1.02 body length per second), which occupies only 2% of the total mass of the robot.

Original languageEnglish
Article numberabo6463
JournalScience Robotics
Issue number71
Publication statusPublished - 2022 Oct 1

Bibliographical note

Funding Information:
Acknowledgments Funding:ThisworkwassupportedbytheNationalResearchFoundationofKorea(NRF)grant fundedbytheKoreangovernment(MSIT;MinistryofScienceandICT)(NRF-2021R1A2C3004151andNRF-2021R1C1C1011872)andthenewfacultyresearchfundofAjou UniversityandtheAjouUniversityresearchfund.Authorcontributions:J.K.,J.-S.K.,andJ.C. conceivedtheideaandinterpretedtheresults.J.K.,C.K.,D.K.,Y .S., S.L.,B.Y ., S.H.,D.K.,J.-S.K.,and J.C.designedandperformedtheexperiments.J.H.conductedtheoreticalcalculationand simulation. J.K., J.-S.K., and J.C. wrote and revised the manuscript. All authors discussed the results and commented on the manuscript. Competing interests: The authors declare that theyhavenocompetinginterests.Dataandmaterialsavailability:Allthedatanecessaryto evaluatetheconclusionsofthepaperarepresentedinthemaintextandtheSupplementary Materials.

Publisher Copyright:
© 2022 The Authors.

ASJC Scopus subject areas

  • General Medicine


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