title: Opto-thermal measurements for the non-invasive, non-occlusive monitoring of in vivo skin condition.
abstract: Summary Opto-thermal transient radiometry (OTTER) is a non-invasive measurement technique, well suited for in vivo skin research. Its excitation and detection wavelengths can be selected to give a high sensitivity to stratum corneum hydration. This is demonstrated with measurements of hydration changes resulting from occlusion with a neoprene cover and with a topical application of an occlusive preparation. In the former case, the hydration was found to recover to normal levels upon exposure to atmospheric conditions in a characteristic time of 15 min. In the latter case, a topical application of petroleum jelly was found to lead to a doubling of stratum corneum hydration over 2h. This ability to measure hydration changes in the presence of topical hydrating agents is thought to be a particularly valuable property of the OTTER technique. With a different choice of excitation and detection wavelengths, OTTER can be used to measure skin thickness, from the surface down to the vascular bed. This technique was used to measure a skin thickness map of the ventral surface of the forearm of a volunteer, showing distinct thickening near the wrist and ulna. Another use of this technique is the study of changes in subcutaneous blood distribution associated with erythema. As a demonstration of this, blood distribution changes brought about by the topical application of a salicylate/nicotinate preparation were studied. The main finding is that the subcutaneous blood spreads towards the surface, with the mean depth decreasing from 63 mum to 55mum.
authors.affiliation: Photophysics Research, School of EE & IE, South Bank University, 103 Borough Rd, London SE1 0AA, England, UK.
authors.forename: R M
authors.initials: RM
authors.lastname: Bindra
authors.forename: R E
authors.initials: RE
authors.lastname: Imhof
authors.forename: J J
authors.initials: JJ
authors.lastname: Andrew
authors.forename: P G
authors.initials: PG
authors.lastname: Cummins
authors.forename: G M
authors.initials: GM
authors.lastname: Eccleston