In-vivo hydration profile mapping of human stratum corneum using fiber-optic optothermal radiometry

We report the development of an instrument, a fiber-optic optothermal transient emission radiometer (OTTER), which overcomes an important limitation in our current bench-top optothermal instrument in being able to perform in-vivo measurements at arbitrary human skin sites. Its main component is a hand-held probe with laser delivery fiber, MCT detector and compact infrared emission focusing optics. This probe can be used to scan the surface of the sample, a process in which optothermal transient signal maps can be measured. The optics design has been optimized using the Zemax ray-tracing software and was found to be 3.4 times more efficient than our current OTTER optics. Preliminary results showing the effect of moisturizing cream as a three-dimensional stratum corneum hydration map is presented.