How it all startedThis idea was first introduced in the 2000s, at the University of Illinois, by Professor John A. Rogers. The scientist envisioned an electronic tattoo in the form of a thin and flexible rubber sheet. It would be placed on the surface of the skin rather than injected permanently. An interesting but far too ambitious concept at the time.Much like paper, human skin is a delicate surface, and although electronic printing has been around for a while, scientists hadn't figured out a way to print on human skin. Earlier versions of flexible electronics were used exclusively as cardiac and brain activity sensors or muscle stimulators.A student implanted a prototype into their pinky fingerElectronic engineering students at Duke University developed a new flexible electronic printing technique that is soft enough to be applied to human skin. One of them, Nick Williams, decided to print two electronically active leads along the underside of his pinky finger and connect them to a small LED light. To demonstrate that the system functions properly even when he bends his finger, he applied a voltage to the circuit, causing the LED to turn on. An amazing demonstration, but there's more...Duke University researchers' electronic printing system opens up new opportunitiesNew conductive tattoo inkEager to take this project further, other researchers improved the process. One study, in particular, introduces the creation of silver nanowires that can be printed at low temperatures, directly onto the skin, using an aerosol. The ink takes less than two minutes to dry and remains conductive even when the surface is bent or moved around.Aesthetic and medical usesBesides making flashing tattoos a possibility, these technological advances could have many more uses in the healthcare sector. For example, we might be able to make bandages with sensors that are tailored to each patient's individual needs.