UV-activated tattoo ink can be switched on and fade in sunlight
Scientists have created a light-sensitive tattoo pigment called PhotoTat that can be illuminated with ultraviolet light and disappears under bright outdoor sun, staying functional in skin for up to 2.2 years.
A research team led by Carson Bruns at the University of Colorado Boulder has engineered a tattoo ink that reacts to specific light wavelengths. The formulation, named PhotoTat, incorporates blue, magenta and yellow pigments with photochromic dyes sealed in polymethyl methacrylate particles. Exposure to a 365-nanometre ultraviolet LED activates the colours in two to three seconds, and the hues can stay visible for hours or days under indoor lighting.
Direct sunlight, however, causes the pigments to lose colour within seconds, effectively concealing the design without removing the material. Laboratory and self-applied skin tests demonstrated that the ink’s three colour channels remained controllable for periods ranging from 1.4 to 2.2 years. Potential applications include reversible body art, temporary concealment of tattoos for professional settings, and medical markings that become visible only during procedures such as radiation therapy.
