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Biomechanical measurements in microscopically thin stratum comeum using acoustics
1Oxford Orthopaedic Engineering Centre, University of Oxford, Oxford, UK.
Summary
Acoustic microscopy accurately measures stratum corneum mechanical properties after reagent exposure. This technique reliably indicates changes in skin layer properties due to substance imbibition.
Area of Science:
- Biophysics
- Materials Science
- Dermatology
Background:
- The stratum corneum, the skin's outermost layer, has critical mechanical properties.
- Measuring these properties at a microscopic level presents significant challenges.
Purpose of the Study:
- To develop and validate a scanning acoustic microscope (SAM) for assessing stratum corneum mechanical property changes.
- To investigate the effects of aqueous reagents on skin layer thickness, density, wave velocity, and elastic constants.
Main Methods:
- Utilized a 650 MHz scanning acoustic microscope (SAM) on 10 µm human skin sections.
- Exposed specimens to glycerol, sodium chloride, and alpha-hydroxy caprylic acid (HCA) solutions.
- Measured acoustic signal transmission parallel to epidermal layers.
Main Results:
- The SAM system provided repeatable and reliable measurements of stratum corneum mechanical property changes.
- Acoustic measurements of thickness and density correlated well with optical and published data.
- Observed discrepancies in elastic moduli trends compared to bulk extensibility tests were noted.
Conclusions:
- The developed SAM is a reliable tool for evaluating stratum corneum mechanical property alterations.
- Differences in elastic moduli trends are attributed to strain rate dependence and varying loading rates in testing.
- Further research is needed to reconcile micro-scale acoustic findings with macro-scale mechanical tests.