The tattoo in reality is a sensor made from graphene, a layer of carbon that’s one-atom thick, with carefully constructed peptides (a short sequence of amino acids) placed onto the surface, allowing it to pick up and detect bacteria individually. The sensor can be used in a variety of different settings, such as in a war zone where soldiers can be quickly diagnosed for bacterial infections from wounds, or in hospitals where it can be used to detect bacteria on a variety of different surfaces.
McAlpine and his team are currently planning on commercializing the graphene sensors although they admit that additional work needs to be done first. For starters, the team would have to shrink the sensors which are currently too big to be practical, and ultimately end up with a sensor that’s small enough to fit on a human tooth.