GoKawiilIf you’ve ever been hooked up to a wearable machine at a doctor’s office, then you’re familiar with the electrodes that are attached to your body to monitor its electrical signals. The problem with these prefabricated metal-based or hydrogel electrodes is that they don’t always stay in place during movement, for long periods or on sweaty or hairy skin.
Penn State University engineers aim to change this with paint-on tattoos that use conductive ink to power sensors for wearable devices such as EEGs, ECGs and EMGs that track brain, heart and muscle activity, respectively.
As reported in a paper published Monday in the Proceedings of the National Academy of Sciences, the engineering team filed a provisional patent for this ink, a water-based solution mixed with polymers and acidic additives that starts out transparent with a glue-like consistency. It can be pigmented with food dye to create different colors for a cute fox or shark that opens its mouth when you open your hand, and it dries on the skin in under 10 minutes. It can later be reapplied or washed off.
Thanks to its customizable, fun nature, these paintable electrodes could be especially beneficial for children who may be more likely to wear a medical device if it’s powered by a temporary tattoo of their favorite character or animal.
Thanks to its customizable nature, the ink can be used like face paint for any design you desire. Wanqing Zhang/Penn State
How the ink powers wearable devices
To connect the ink to sensors, there’s a porous silver textile with connective electrodes. Before your painted-on tattoo dries, the textile is placed on the design so that it will stick to the skin. Then, the textile is connected to a port on a wearable monitoring device. The latter is taped to the skin beneath clothing.
Electrical signals collected by the ink are sent through the textile to the monitoring device, which then transmits the data to a computer via Bluetooth.
When the conductive ink is paired with a silver textile, it can be attached to a wearable medical device. Wanqing Zhang/Penn State
“The big idea behind this is that in the future, you could potentially have a more expensive sensing module that remains separate from the system, but the electrodes themselves can be disposable. A single bottle of ink could provide enough material to paint multiple electrodes over the course of several days or a week,” said Larry Cheng, the paper’s corresponding author and a James L. Henderson Jr. memorial professor of engineering science and mechanics at Penn State, in a press release.
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