A tiny paper-thin sensor created from graphene, which can be `tattooed' onto teeth, works as an ultra-sensitive `early warning system' for disease. In tests, a student breathed onto the sensor - actually implanted on a cow's tooth - and it picked up molecules of bacteria on his breath. Michael McAlpine and his team at Princeton, who developed the `tooth tattoo', believe the sensors could be used for military personnel in the field to determine whether a wound has become infected, or in hospitals where patients with weakened immune systems are extra vulnerable to bacteria, the Daily Mail reported. The scientists created the remote chemical sensor with graphene, a one-atom-thick layer of carbon, which is very sticky and has a super-sensitive surface. They then planted carefully constructed peptides (a sequence of amino acids) onto the surface of graphene. McAlpine and his team have shown the sensors can detect bacteria individually picking them up like Velcro. McAlpine is currently planning to license and commercialise the device.