While it may seem like tattoos are the norm now, no one has ink like this. A team from the University of Illinois led by John Rogers has devised a method to actually install LED lights under the skin. The research, published today in Nature Materials, saw the team develop flexible arrays 2.5 μm thick and 100 x 100 μm square which are currently smaller than any commercially available array.
In their research, the team printed circuits “directly onto a rigid glass substrate and then transferred them to an inexpensive biocompatible polymer called poly(dimethylsiloxane) (PDMS) to create a mesh-like array of LEDs and photodetectors.”
In short, the university team has allowed LEDs to be placed under the skin while allowing for stretching and twisting by as much as 75 percent. As the whole substrate is encased in thin silicon rubber, the ‘LED tattoo’ is also waterproof. The uses are numerous. As well as becoming the latest in tattoo evolution, sub dermal illumination could also aid in the monitoring of wounds, spectroscopy, colour-coding robots and photodynamic drug therapy.
Rogers said of his team’s research that commercializing the technology was “incredibly appealing” and he couldn’t wait to see the impact it has. The team had previously tested the LEDs by integrating a sheet into the fingertip of a vinyl glove, which was then immersed in soapy water.