Elastohydrodynamic friction of robotic and human fingers on soft micropatterned substrates.

Journal: Nature materials
PMID: 33927390

Abstract

Frictional sliding between patterned surfaces is of fundamental and practical importance in the haptic engineering of soft materials. In emerging applications such as remote surgery and soft robotics, thin fluid films between solid surfaces lead to a multiphysics coupling between solid deformation and fluid dissipation. Here, we report a scaling law that governs the peak friction values of elastohydrodynamic lubrication on patterned surfaces. These peaks, absent in smooth tribopairs, arise due to a separation of length scales in the lubricant flow. The framework is generated by varying the geometry, elasticity and fluid properties of soft tribopairs and measuring the lubricated friction with a triborheometer. The model correctly predicts the elastohydrodynamic lubrication friction of a bioinspired robotic fingertip and human fingers. Its broad applicability can inform the future design of robotic hands or grippers in realistic conditions, and open up new ways of encoding friction into haptic signals.

Authors

  • Yunhu Peng
    Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC, USA.
  • Christopher M Serfass
    Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC, USA.
  • Anzu Kawazoe
    Department of Electrical and Computer Engineering, University of California-Santa Barbara, Santa Barbara, CA, USA.
  • Yitian Shao
    Department of Electrical and Computer Engineering, University of California-Santa Barbara, Santa Barbara, CA, USA.
  • Kenneth Gutierrez
  • Catherine N Hill
    Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC, USA.
  • Veronica J Santos
  • Yon Visell
    Media Arts and Technology Program, Department of Electrical and Computer Engineering, California NanoSystems Institute, and Center for Polymers and Organic Solids, University of California, Santa Barbara, Santa Barbara, California.
  • Lilian C Hsiao
    Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC, USA. lilian_hsiao@ncsu.edu.

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