A team of researchers from Carnegie Mellon University (CMU) designed a set of temporary electronic tattoos which could replace a lot of gadgets, starting with wearables. We can’t completely rely on our wearables due to their short battery life, inaccurate blood pressure measurements and several other reasons. However, instead of actually wearing a smartwatch, it could be printed right on the skin.
The concept of temporary tattoos is not a new one. However, all previous approaches to the method were slow and fairly expensive. To make it work, the tattoo must be easy to manufacture and even easier to apply. The team behind the temporary electronic tattoos hopes to have finally achieved success with the new design.
“We’re reporting a new way of creating electronic tattoos,” CMU’s Carmel Majidi said in a video from the university. “These are circuits that are printed on temporary tattoo film. We print circuits made of silver nanoparticles, and then what we do is we coat those silver nanoparticles with a liquid metal alloy. The liquid metal fuses with the silver to create these conductive wires on the tattoo; the tattoo can easily be transferred to skin, and the conductivity is high enough to support digital circuit functionality.”
What makes this approach to temporary electronic tattoos more advantageous than previous attempts is that researchers could merge inkjet-printed nanoparticle patterns with other metals like gallium indium alloy without experimenting with different temperatures.
“This is a breakthrough in the printed electronics area,” he said in a statement. “Removing the need for high temperature sintering makes our technique compatible with thin-film and heat sensitive substrates.”
Depending on what purpose they will be used for, the temporary tattoos can be attached to even the most fragile objects like a temporary tattoo film or bandage. Because they are so flexible, the tattoos will keep functioning when deformed. Moreover, they cannot be rubbed off easily. They can stand up to twisting and straining greater than 30%, which is the typical stretching ability of our skin, according to the team. The tattoos can be easily applied to curved 3D surfaces, including a 3D model of a human brain and a lemon.
The project is mostly applicable in medicine, since these temporary electronic tattoos capable of replacing finger clips or an armband heart monitor. They could even include chemical sensors to test blood sugar and inform the user if their sugar is critically low or high.
Last year, researchers came up with temporary tattoos which could be placed on skin and perform blood tests like blood sugar and dehydration testing. The tattoos would then reveal the results by changing color. This would allow patients to easily see their test results without actually going to see their doctor. The newly-designed temporary electronic tattoos could have similar applications.
The study was published in the journal Advanced Materials.