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Light-Activated Tattoos: Ink That Can Appear and Disappear with Light
By Drooid · · How we work
Light-Activated Tattoos: New Ink Breakthrough
Researchers at the University of Colorado have created a tattoo ink that changes visibility when exposed to specific wavelengths of light. The method, dubbed “PhotoTat,” uses photochromic dyes that become coloured under ultraviolet illumination and revert to transparency under bright visible light. The pigment particles are injected into the dermis with the same needles and machines used for conventional tattoos, but the colour can be switched on and off repeatedly.
How the Technology Works
PhotoTat relies on dyes that shift from a transparent to a coloured state when they absorb ultraviolet light. Sixteen distinct colours have been produced, which combine into at least 300 discernible shades. White cannot be used because it reflects rather than absorbs light. The researchers note that the blue dye gradually develops a permanent purplish hue after many activation cycles, and a true cyan colour has not yet been achieved. Users would need to apply sunscreen to prevent accidental activation from sunlight.
Safety Concerns and Expert Opinions
Carson Bruns emphasizes that the polymer encapsulating the dyes is non-toxic and has a long history in permanent biomedical implants, though the toxicity of the colour-changing dyes themselves remains unknown. He points out that the health risks of traditional tattoo pigments are similarly uncertain. Signe Bedsted Clemmensen of the University of Southern Denmark warns that any foreign substance in the skin, visible or invisible, can be linked to cancer and other health issues, citing recent reports of red ink causing hair loss and sweating problems.
Potential Uses and Limitations
The reversible nature of PhotoTat could benefit medical applications, such as temporary markings that guide radiation therapy without leaving permanent scars. Cosmetic users might hide designs from judgmental observers and reveal them at will. However, extensive safety testing is required before the technology can reach the public market, and the need for sunscreen adds a practical limitation.
Verbatim Quote
- “You can simply turn the tattoo off whenever you don’t want to see it and it disappears from view,” — Carson Bruns, them invisible researcher