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.

The Impact of Feet Callosities, Arm Posture, and Usage of Electrolyte Wipes on Body Composition by Bioelectrical Impedance Analysis in Morbidly Obese Adults

“…The rate of water accumulation at BIA contact sites may be affected during measurements, as skin contact with the electrodes disrupts natural transpiration [ 15 , 16 ]. The rate of water accumulation in the stratum corneum can be further exacerbated by the presence of callosities, as new stratum corneum forming underneath calluses is less hydrated than normal [ 16 ]. To our knowledge, no study has looked at the potential impact of common feet callosities, arm posture, and use of electrolyte wipes on body composition measurements derived from BIA.…”