Tattoo ink vanishes in sunlight, stays switchable in skin for up to 2.2 years

A new study published in the journal Nature Communications has revealed a temporary tattoo ink that can vanish in sunlight and reappear when exposed to a specific wavelength of light. The ink, developed by researchers at the University of California, Los Angeles, uses a combination of organic dyes and a light-sensitive material to create the effect. The tattoos can last for up to 2.2 years before fading completely.