UV tattoo

UV tattoos were first used for animal identification markers. UV tattoos are sometimes chosen by people who do not want tattoos visible under normal light for professional or social reasons. To support detection and treatment of potential skin cancer, the site of a biopsy can be marked with a UV tattoo to ensure correct identification of that site afterward. A researcher proposed using a UV tattoo to mark a password for a pacemaker (or other implantable medical device) on the skin, enabling medical personnel to unlock the device if needed, without requiring the person to wear a medical bracelet. Researchers have studied creating smart tattoos with fluorescent glucose biosensors, where "the tattoo ink is functionalized with microparticles which produce fluorescence when the concentration of a biomarker in the interstitial fluid increases." Microneedle patches could be used to deliver injections, such as vaccines, while simultaneously tattooing a simple image or year in ultraviolet ink to record information about the injection while preserving the patient's privacy. Photochromic tattoos that react to UV light to change the color of the pigment itself, instead of exhibiting fluorescence, have been patented. One potential use of photochromic ink is to tattoo "freckles" that only appear if that area of skin has had a certain amount of UV exposure, to help the person monitor sun exposure for skin cancer prevention. == Appearance and application ==

A tattoo made with UV ink becomes visible under blacklight, when it fluoresces in colors depending on the ink chosen, typically white or purple. UV inking is more difficult than using conventional inks and requires a longer application process. For UV tattoos this may mean the tattoo becomes more visible under visible light or may not glow in black lighting. == Formulas and safety ==

A typical blacklight ink formula includes microspheres of poly(methyl methacrylate) (PMMA) containing fluorescent dye. Another example of a commercially available ink contained a coumarin-based fluorescent dye in a polymer matrix containing melamine formaldehyde. Companies may claim FDA approval, but any approval of UV inks is for animal identification purposes rather than human use. In one case, inflammation (a skin manifestation of sarcoidosis) happened five years after receiving a UV tattoo made with PMMA. Some tattoo artists purchase and use UV inks from manufacturers they consider reputable, especially manufacturers that provide Material Safety Data Sheets with information about ink ingredients. UV tattoos may be difficult to remove with standard laser tattoo removal because of the lack of pigment in the skin. == References ==