Elastic modulus and viscoelastic properties of full thickness skin characterised at micro scales

Michael L. Crichton, Xianfeng Chen, Han Huang, Mark A.F. Kendall

Research output: Contribution to journalArticlepeer-review

51 Citations (Scopus)

Abstract

The recent emergence of micro-devices for vaccine delivery into upper layers of the skin holds potential for increased immune responses using physical means to target abundant immune cell populations. A challenge in doing this has been a limited understanding of the skin elastic properties at the micro scale (i.e. on the order of a cell diameter; ~10 μm). Here, we quantify skin's elastic properties at a micro-scale by fabricating customised probes of scales from sub- to super-cellular (0.5 μm-20 μm radius). We then probe full thickness skin; first with force-relaxation experiments and subsequently by elastic indentations. We find that skin's viscoelastic response is scale-independent: consistently a ~40% decrease in normalised force over the first second, followed by further 10% reduction over 10 s. Using Prony series and Hertzian contact analyses, we determined the strain-rate independent elastic moduli of the skin. A high scale dependency was found: the smallest probe encountered the highest elastic modulus (~30 MPa), whereas the 20 μm radius probe was lowest (below 1 MPa). We propose that this may be a result of the load distribution in skin facilitated by the hard corneocytes in the outermost skin layers, and softer living cell layers below.

Original languageEnglish
Pages (from-to)2087-2097
Number of pages11
JournalBiomaterials
Volume34
Issue number8
DOIs
Publication statusPublished - Mar 2013

Keywords

  • Elastic modulus
  • Indentation
  • Micro-probe
  • Skin
  • Viscoelastic

ASJC Scopus subject areas

  • Bioengineering
  • Ceramics and Composites
  • Biophysics
  • Biomaterials
  • Mechanics of Materials

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