Natures design of hierarchical superhydrophobic surfaces of a water strider for low adhesion and low-energy dissipation

Yewang Su, Baohua Ji*, Yonggang Huang, Keh Chih Hwang

*Corresponding author for this work

Research output: Contribution to journalArticle

82 Citations (Scopus)

Abstract

The mechanics of wet adhesion between a water striders legs and a water surface was studied. First, we showed that the nanoscale to microscale hierarchical surface structure on striders legs is crucial to the stable water-repellent properties of the legs. The smallest structure is made for the sake of a stable Cassie state even under harsh environment conditions, which sets an upper limit for the dimension of the smallest structure. The maximum stress and the maximum deformation of the surface structures at the contact line are size-dependent because of the asymmetric surface tension, which sets a lower limit for the dimension of the smallest structure. The surface hierarchy can largely reduce the adhesion between the water and the legs by stabilizing the Cassie state, increasing the apparent contact angle, and reducing the contact area and the length of the contact line. Second, the processes of the legs pressing on and detaching from the water surface were analyzed with a 2D model. We found that the superhydrophobicity of the legs surface is critically important to reducing the detaching force and detaching energy. Finally, the dynamic process of the legs striking the water surface, mimicking the maneuvering of water striders, was analyzed. We found that the large length of the legs not only reduces the energy dissipation in the quasi-static pressing and pulling processes but also enhances the efficiency of energy transfer from bioenergy to kinetic energy in the dynamic process during the maneuvering of the water striders. The mechanical principles found in this study may provide useful guidelines for the design of superior water-repellent surfaces and novel aquatic robots.

Original languageEnglish (US)
Pages (from-to)18926-18937
Number of pages12
JournalLangmuir
Volume26
Issue number24
DOIs
StatePublished - Dec 21 2010

Fingerprint

Energy dissipation
adhesion
surface water
Adhesion
energy dissipation
Water
water
pressing
pulling
Surface structure
robots
microbalances
hierarchies
interfacial tension
kinetic energy
energy transfer
Kinetic energy
Energy transfer
Contacts (fluid mechanics)
Contact angle

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Spectroscopy
  • Electrochemistry

Cite this

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title = "Natures design of hierarchical superhydrophobic surfaces of a water strider for low adhesion and low-energy dissipation",
abstract = "The mechanics of wet adhesion between a water striders legs and a water surface was studied. First, we showed that the nanoscale to microscale hierarchical surface structure on striders legs is crucial to the stable water-repellent properties of the legs. The smallest structure is made for the sake of a stable Cassie state even under harsh environment conditions, which sets an upper limit for the dimension of the smallest structure. The maximum stress and the maximum deformation of the surface structures at the contact line are size-dependent because of the asymmetric surface tension, which sets a lower limit for the dimension of the smallest structure. The surface hierarchy can largely reduce the adhesion between the water and the legs by stabilizing the Cassie state, increasing the apparent contact angle, and reducing the contact area and the length of the contact line. Second, the processes of the legs pressing on and detaching from the water surface were analyzed with a 2D model. We found that the superhydrophobicity of the legs surface is critically important to reducing the detaching force and detaching energy. Finally, the dynamic process of the legs striking the water surface, mimicking the maneuvering of water striders, was analyzed. We found that the large length of the legs not only reduces the energy dissipation in the quasi-static pressing and pulling processes but also enhances the efficiency of energy transfer from bioenergy to kinetic energy in the dynamic process during the maneuvering of the water striders. The mechanical principles found in this study may provide useful guidelines for the design of superior water-repellent surfaces and novel aquatic robots.",
author = "Yewang Su and Baohua Ji and Yonggang Huang and Hwang, {Keh Chih}",
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Natures design of hierarchical superhydrophobic surfaces of a water strider for low adhesion and low-energy dissipation. / Su, Yewang; Ji, Baohua; Huang, Yonggang; Hwang, Keh Chih.

In: Langmuir, Vol. 26, No. 24, 21.12.2010, p. 18926-18937.

Research output: Contribution to journalArticle

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