Scientists have unveiled a novel tattoo ink that behaves like a light‑controlled switch, allowing colors and designs embedded beneath the skin to be turned on, altered, or hidden without the need for painful removal procedures. The technology, marketed under the name PhotoTat, was detailed in a study released on October 9 in the journal Matter & Light.
How the technology works
PhotoTat relies on three primary pigments—blue, magenta and yellow—each formulated with photochromic dyes. These dyes are compounds that modify their molecular structure when exposed to specific wavelengths of light, thereby changing color. To protect the dyes and make them suitable for intradermal use, they are encapsulated in nanoparticles composed of polymethyl methacrylate (PMMA), a medical‑grade plastic already employed in implants and dermal fillers.
Activation is achieved with a 365‑nanometer ultraviolet LED. According to associate professor Carson Bruns of the University of Colorado Boulder, the ink responds within two to three seconds of exposure. Once switched on, the colors can remain visible for hours or even days under normal indoor lighting. However, bright outdoor sunlight provides enough energy to reverse the reaction in a matter of seconds, effectively erasing the image while the pigment itself stays in the skin.
The research team demonstrated that each of the three color channels retained their switchable properties for between 1.4 and 2.2 years after being tattooed, suggesting long‑term durability. Because each pigment responds to a different light wavelength—magenta can be triggered by green light, yellow by blue light, and so forth—users can selectively illuminate portions of a design, creating a palette that can shift from a purple cherry to a cluster of yellow hearts, for example.
Potential uses and market outlook
Beyond novelty, the reversible nature of PhotoTat could appeal to individuals who enjoy body art but are concerned about its permanence. Bruns described the ink as a “fun and playful” addition for people with multiple tattoos who might want to hide or reveal elements for work, family gatherings, or other social contexts. The ink can also be layered with conventional black tattoo ink, allowing hidden patterns to emerge only when activated.
Medical applications are a key focus of the research. Permanent marks placed on patients undergoing radiation therapy help clinicians align treatment beams, yet those marks remain visible afterward, serving as a reminder of the procedure. A PhotoTat‑based mark could be turned on only when needed, then hidden from view. Similar concepts could be used during surgery to display temporary guides that disappear once the operation concludes.
Bruns has also explored other smart‑tattoo concepts, such as dosimeter tattoos that change color in response to ultraviolet exposure or dangerous gamma radiation, potentially offering real‑time monitoring for astronauts, nuclear engineers, or outdoor workers.
Commercially, only the purple formulation of PhotoTat has progressed through third‑party medical testing and is currently available for purchase. The tested batch met safety standards, but the price remains high at roughly $100 for a small bottle. Bruns hopes that continued research will bring the remaining colors to market and reduce production costs, making the technology more accessible.
In summary, PhotoTat introduces a reversible, light‑responsive approach to tattooing that blends artistic flexibility with practical medical uses. While still early in its commercial journey, the ink’s ability to appear and vanish on command could reshape how people think about permanent body art.
Helene Elliott is the Lead Science & Space Reporter at News Raise. She reports on aerospace missions, astrophysics discoveries, quantum research, and environmental technology.
