| abstract |
A tattoo that is invisible to the naked eye until the tattoo is exposed to ultraviolet radiation, whereupon the tattoo becomes visible to the naked eye, and which reverts to invisible upon removal from exposure to ultraviolet radiation. The tattoo is formed by embedding in the skin a mixture including a non-pigmented carrier and one or more photochromic compounds that undergo a photochemical transformation from colorless to colored upon exposure to ultraviolet radiation, and which revert to colorless upon removal from exposure to ultraviolet radiation. |