Next a Transepidermal Water Loss Meter (Tewameter) will be used to measure the water evaporation gradient on the skin. Measurements will be performed with non-invasive devices that have been widely used for the study of skin barrier function. Each device has a flat-top electrode (approximate diameter of 1cm) that will come in contact with the skin surface during measurements. This device does not deliver any energy into the skin. The subjects will not experience discomfort during and after the measurements. The electrode tip will be cleaned with alcohol wipes between subjects.