Opto-thermal measurement of barrier cream residence time on skin in-vivo

We report the non-invasive opto-thermal measurement of the residence time of a barrier cream on in-vivo skin. These measurements revealed an approximately exponential decrease of cream layer thickness with a 1/e disappearance time of similar to 60 minutes. Measurements on a cream layer on a polymer substrate under otherwise similar conditions confirmed that penetration into the stratum corneum, rather than abrasion or evaporative loss, was the main cause of the observed disappearance.