High-Power Hydro-Actuators Fabricated from Biomimetic Carbon Nanotube Coiled Yarns with Fast Electrothermal Recovery

Wonkyeong Son, Jae Myeong Lee, Shi Hyeong Kim, Hyeon Woo Kim, Sung Beom Cho, Dongseok Suh, Sungwoo Chun, Changsoon Choi

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12 Scopus citations


Bioinspired yarn/fiber structured hydro-actuators have recently attracted significant attention. However, most water-driven mechanical actuators are unsatisfactory because of the slow recovery process and low full-time power density. A rapidly recoverable high-power hydro-actuator is reported by designing biomimetic carbon nanotube (CNT) yarns. The hydrophilic CNT (HCNT) coiled yarn was prepared by storing pre-twist into CNT sheets and subsequent electrochemical oxidation (ECO) treatment. The resulting yarn demonstrated structural stability even when one end was cut off without the possible loss of pre-stored twists. The HCNT coiled yarn actuators provided maximal contractile work of 863 J/kg at 11.8 MPa stress when driven by water. Moreover, the recovery time of electrically heated yarns at a direct current voltage of 5 V was 95% shorter than that of neat yarns without electric heating. Finally, the electrothermally recoverable hydro-actuators showed a high actuation frequency (0.17 Hz) and full-time power density (143.8 W/kg).

Original languageEnglish
Pages (from-to)2470-2478
Number of pages9
JournalNano Letters
Issue number6
StatePublished - 23 Mar 2022

Bibliographical note

Funding Information:
This work was supported by the Korea Institute of Industrial Technology (KITECH EH220002) and the Basic Science Research Programs through the National Research Foundation of Korea (NRF-2017R1A6A3A04004987 and NRF-2021R1A2C2005281).

Publisher Copyright:
© 2022 American Chemical Society. All rights reserved.


  • biomimetics
  • carbon nanotube yarn
  • electrothermal recovery
  • hydro-actuator
  • power density


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