First Light Emitting Tattoo Emerges

Scientists have created a temporary tattoo with light-emitting technology used in TV and smartphones screen, paving the way for a 'smart tattoo'. A relife for tattoo lovers that fear breaking their skin barrier, including getting an infection, skin cancers and more.

UCL and the IIT  (Italian Institute of Technology), scientist created the technology, which uses organic light-emitting diodes (OLEDs) that is applied the same way as water transfer tattoos. That is, the OLEDs are fabricated on temporary tattoo paper and transferred to a new surface by being pressed on to it and dabbed with water.

The Researcher described the process in a journal "Advanced Electronic Materials" saying that it could be combined with other tattoos too and could be tattooed on packaging or fruits to signal when a product has passed its expiry date or soon become inedible, or used for fashion in the form of glowing tattoos.

Professor Franco Cacialli (UCL Physics & Astronomy) said, "The tattooable OLEDs that we have demonstrated for the first time can be made at scale and very cheaply. They can be combined with other forms of tattoo electronics for a very wide range of possible uses. These could be for fashion – for instance, providing glowing tattoos and light-emitting fingernails. In sports, they could be combined with a sweat sensor to signal dehydration."

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Cacialli described the light-emitting tattoo as being able to tell when there is a change in a patients condition and challenges will include compressing the OLEDs as much as possible to stop them from fading quickly.

“In healthcare, they could emit light when there is a change in a patient’s condition – or, if the tattoo was turned the other way into the skin, they could potentially be combined with light-sensitive therapies to target cancer cells, for instance," Cacialli said.

“Our proof-of-concept study is the first step. Future challenges will include encapsulating the OLEDs as much as possible to stop them from degrading quickly through contact with air, as well as integrating the device with a battery or supercapacitor.”

The OLED device consists of an electroluminescent polymer in between electrodes. It is developed in 2.3 micrometers thicks in total about a third of the length of a single red blood cell. An insulating layer is placed in between the electrodes and the commercial tattoo paper.

The light-emitting polymer is 76 nanometres thick - a nanometre is a millionth of a millimeter - and was created using a technique called spin-coating, where the polymer is applied to a substrate which is spun at high speed, producing an extremely thin and even layer.

The tattooable OLEDs, emits green light, onto a pane of glass, a plastic bottle, an orange, and paper packaging when applied

The senior author of the journal, Professor Virgilio Mattoli, a researcher at the Italian Institute of Technology said, the light-emitting tattoo is a fast-growing field of research and the advantage is that it is low cost.

Senior author of the journal, Professor Virgilio Mattoli, a researcher at the Italian Institute of Technology said: “Tattoo electronics is a fast-growing field of research. At the Italian Institute of Technology, we have previously pioneered electrodes that we have tattooed onto people’s skin that can be used to perform diagnostic tests such as electrocardiograms. The advantage of this technology is that it is low-cost, easy to apply and use, and washes off easily with soap and water.”

OLEDs were first used in a flatscreen TV 20 years ago. Among the advantages of the technology are that they can be used on flexible, bendy surfaces and that they can be made from liquid solvents. This means they are printable, providing a cheap way to create bespoke new OLED designs.