The Dermal Abyss tattoo inks change color according to the chemistry of the body’s interstitial fluid, which can be used as a surrogate for constituents of the blood. Inks developed so far change from green to brown as glucose concentration increases. The team also developed a green ink, viewable under blue light, that grows more intense as sodium concentration rises, an indication of dehydration. Researchers tattooed the inks onto segments of pig skin and noted how they changed color or intensity in response to different biomarkers.
Jiang and Yetisen said that once the bugs are worked out, the applications for biologically-sensitive ink are fairly broad. Inks, Yetisen said, could be incorporated into long-lasting tattoos for chronic conditions or into temporary designs for shorter-duration monitoring. Ink can even be invisible, Yetisen said, readable under only particular kinds of light. That light could come from something as ubiquitous as a smartphone.