Conference Contribution Details
Keynote Lecture, SCVII & Skin Forum Conference, Cardiff 2012.
Stratum corneum (SC) hydration is an important property associated with skin health. But whilst the symptoms of dry skin are easily recognised, the reliable measurement of SC hydration remains a challenge. This is partly because the SC itself is physically and chemically heterogeneous, partly because other properties such as scaling swelling and water binding change with hydration, partly because external and internal factors affect hydration and partly because hydration varies from person to person, site to site and time to time. In addition, any single-parameter description of SC hydration is bound to be inadequate, given the fact that it is wet on the inside and dry on the outside.
The talk will review the field of SC hydration measurement from a physicist’s perspective. I will start with in-vitro measurements on excised SC, where the relationship between SC hydration and ambient humidity gives valuable insights. This is developed into an in-vivo model of the SC that, despite being highly over-simplified, nevertheless provides a useful guide for interpreting SC hydration measurements.
There are many approaches to in-vivo SC hydration measurement, but they can be classified into two broad groups: optical and electrical. Optical techniques include confocal Raman spectroscopy, photo-acoustic, photo-thermal, ATR-FTIR and near-infrared diffuse reflectance. Electrical techniques include conductance, capacitance, impedance and magnetic resonance. I will review these in an attempt to identify their +ve and -ve attributes.
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