From the MIT press office:

MIT researchers have now developed a novel way to record a patient's vaccination history: storing the data in a pattern of dye, invisible to the naked eye, that is delivered under the skin at the same time as the vaccine.

"In areas where paper vaccination cards are often lost or do not exist at all, and electronic databases are unheard of, this technology could enable the rapid and anonymous detection of patient vaccination history to ensure that every child is vaccinated," says Kevin McHugh, a former MIT postdoc who is now an assistant professor of bioengineering at Rice University.

The researchers showed that their new dye, which consists of nanocrystals called quantum dots, can remain for at least five years under the skin, where it emits near-infrared light that can be detected by a specially equipped smartphone.

McHugh and former visiting scientist Lihong Jing are the lead authors of the study, which appears today in Science Translational Medicine. Ana Jaklenec, a research scientist at MIT's Koch Institute for Integrative Cancer Research, and Robert Langer, the David H. Koch Institute Professor at MIT, are the senior authors of the paper...