Validation of a novel smartphone application-enabled, patient-operated skin barrier device.

Background: Transepidermal water loss (TEWL) and surface capacitance measure skin barrier permeability and stratum corneum (SC) hydration, respectively, and are frequently utilized in atopic dermatitis clinical trials. Many barrier devices are costly and often used only in the academic setting. GPSkin is a low-cost, patient-operated device that measures both TEWL and SC hydration.