In Vivo Skin Solvent Penetration Measurements Using Opto-thermal Radiometry and Fingerprint Sensor

This latest study on in vivo transdermal drug delivery by using opto-thermal radiometry and a capacitance-based fingerprint sensor is presented. A small amount of solvent was applied on the test sites of a volar forearm for a few minutes; opto-thermal measurements and fingerprint sensor measurements were performed both before the solvent application and periodically after. The results showed that, by selecting different detection wavelengths, opto-thermal radiometry could give the information either on the water concentration within skin or the solvent concentration within skin. The capacitance-based fingerprint sensor could clearly visualize solvent penetration through in vivo human skin, as it generated dynamic two-dimensional (2D) images of solvent distribution within skin, and combining with tape stripping, it was also possible to get solvent 3D depth profiles within skin. The correlation between opto-thermal transient emission radiometry and fingerprint sensor measurements was also evaluated.