Wearables have taken lots of different shapes, but electronic tattoos and second-skins have the potential to be the most convenient option of the lot. Looking to take on-skin technology beyond the medical monitoring arena, Microsoft Research and MIT are exploring the potential for functional temporary tattoos made from gold leaf that offer input, display and wireless communications capabilities, while looking fabulous.

Although a lot of time has been dedicated to investigating medical on-skin technologies, Microsoft Research and MIT were more interested in creating cost-effective on-skin user interfaces for those with an eye for fashion. With this in mind, they developed the DuoSkin fabrication process that makes use of cheap materials and doesn't rely on any complex manufacturing procedures so designs can be easily customized.

Making a piece of DuoSkin "jewellery" is a fairly simple process. The conductive gold leaf circuits can be designed using regular 2D graphic design tools, and can be applied to a piece of store-bought tattoo paper. Although gold leaf might not be something we see every day, it's also not very expensive, so making use of its conductive properties won't break the bank.

Application is no more complex than for a regular temporary tattoo, but once applied it is far more useful than a regular stick on. The research team has demonstrated three potential uses for the technology: as touch-sensitive input devices, as a color-changing display, and for wireless communications.

In terms of a touch interface, the team tested different types of sliders and buttons, with both continuous sliders and less precise (but simpler) setups proving workable despite requiring an Arduino mini controller and a small LiPo battery. Interestingly, tests showed copper was far less durable than gold leaf when being poked and prodded by the wearer, making gold leaf the first-choice for the tattoos – it was also preferred over copper tape and thread for aesthetic purposes.

Using thermochromic pigments, which switch between two different colors in response to changes in temperature, the team also demonstrated a tattoo that changes color when heated above the wearer's normal body temperature, thereby allowing dynamic designs.

To demonstrate the potential for tattoos to be used to communicate wirelessly with other devices, the team paired a passively-powered NFC chip with a gold leaf coil. This could allow people to wear their movie ticket on their arm or make payments with a wave of their hand. All up, researchers estimate a 3 x 4 cm (1 x 1.5 in) NFC unit would cost less than US$2.50.

The team also "highlighted" the purely decorative potential of the technology by embedding LEDs into a tattoo that resembled an on-skin necklace.

As with regular tattoos, the researchers believe that simple wearer customization is essential for on-skin technology to reach wider adoption. The DuoSkin fabrication process and the personal aesthetic principle it embraces could be the key to delivering more functional skin art.

Examples of the DuoSkin tattoos can be seen in the video below.

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