Wearable Surface-Lighting Micro-Light-Emitting Diode Patch for Melanogenesis Inhibition

Abstract

Wearable light-emitting diode (LED)-based phototherapeutic devices have recently attracted attention as skin care tools for wrinkles, acne, and hyperpigmentation. However, the therapeutic effectiveness and safety of LED stimulators are still controversial due to their inefficient light transfer, high heat generation, and non-uniform spot irradiation. Here, a wearable surface-lighting micro-LED (S mu LED) photostimulator is reported for skin care and cosmetic applications. The S mu LEDs, consisting of a light diffusion layer (LDL), 900 thin film mu LEDs, and polydimethylsiloxane (PDMS), achieve uniform surface-lighting in 2 x 2 cm(2)-sized area with 100% emission yields. The S mu LEDs maximize photostimulation effectiveness on the skin surface by uniform irradiation, high flexibility, and thermal stability. The S mu LED's effect on melanogenesis inhibition is evaluated via in vitro and in vivo experiments to human skin equivalents (HSEs) and mouse dorsal skin, respectively. The anti-melanogenic effect of S mu LEDs is confirmed by significantly reduced levels of melanin contents, melan-A, tyrosinase, and microphthalmia-associated transcription factor (MITF), compared to a conventional LED (CLED) stimulator.