Reversible underwater adhesion for soft robotic feet by leveraging electrochemically tunable liquid metal interfaces

Hongda Lu, Guolin Yun, Tim Cole, Yiming Ouyang, Hongtai Ren, Jian Shu, Yuxin Zhang, Shiwu Zhang, Michael D. Dickey, Weihua Li, Shi-Yang Tang

Research output: Contribution to journalArticlepeer-review


Soft crawling robots have potential applications for surveillance, rescue, and detection in complex environments. Despite this, most existing soft crawling robots either use nonadjustable feet to passively induce asymmetry in friction to actuate or are only capable of moving on surfaces with specific designs. Thus, robots often lack the ability to move along arbitrary directions in a two-dimensional (2D) plane or in unpredictable environments such as wet surfaces. Here, leveraging the electrochemically tunable interfaces of liquid metal, we report the development of liquid metal smart feet (LMSF) that enable electrical control of friction for achieving versatile actuation of prismatic crawling robots on wet slippery surfaces. The functionality of the LMSF is examined on crawling robots with soft or rigid actuators. Parameters that affect the performance of the LMSF are investigated. The robots with the LMSF prove capable of actuating across different surfaces in various solutions. Demonstration of 2D locomotion of crawling robots along arbitrary directions validates the versatility and reliability of the LMSF, suggesting broad utility in the development of advanced soft robotic systems.
Original languageEnglish
Pages (from-to)37904–37914
JournalACS Applied Materials & Interfaces
Issue number31
Early online date28 Jul 2021
Publication statusPublished - 11 Aug 2021


  • tunable interfaces
  • liquid metal
  • EGaIn
  • crawling robots
  • soft robotics


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