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Microindentation and nanoindentation of human fingernails at varying relative humidity

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Abstract

The indentation properties of human fingernails at varying humidity are reported. The samples were indented using both microindentation, to obtain their Vickers hardness and also nanoindented using a Berkovich indenter tip. The relative humidity (RH) of the samples was controlled by using salt solutions with a sealed and enclosed environment surrounding the testing equipment. It was shown that the Vickers hardness of the samples is sensitive to RH, with recovery of the nail material more readily occurring for nails tested at >55% RH. This recovery mechanism is discussed in terms of the structure of the nails, and this approach is also suggested as a technique for following recovery mechanisms in natural materials under varying humidity. The hardness obtained by nanoindentation is similar to previously published data, but does not change with humidity. The modulus of the nails is also insensitive to relative humidity, but in the same range as the value derived from the microindentation tests.

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Authors and Affiliations

  1. Materials Science Centre, School ofMaterials, University of Manchester, Manchester, M1 7HS, United Kingdom

    Laura Farran & Stephen J. Eichhorn

  2. Faculty of Life Sciences, University of Manchester, Manchester, M13NJ, United Kingdom

    A. Roland Ennos

Authors
  1. Laura Farran
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  2. A. Roland Ennos
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  3. Stephen J. Eichhorn
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Correspondence to Stephen J. Eichhorn.

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Farran, L., Ennos, A.R. & Eichhorn, S.J. Microindentation and nanoindentation of human fingernails at varying relative humidity. Journal of Materials Research 24, 980–984 (2009). https://doi.org/10.1557/jmr.2009.0119

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  • DOI: https://doi.org/10.1557/jmr.2009.0119

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