Electronics and biological cells 3D printed directly on skin

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Researchers at the University of Minnesota have used a customised, low-cost 3D printer to print electronics on a real hand for the first time. The technology could be used by soldiers on the battlefield to print temporary sensors on their bodies to detect chemical or biological agents or solar cells to charge essential electronics.

Michael McAlpine, Associate Professor of Mechanical Engineering at the University of Minnesota, said: “We imagine that a soldier could pull this printer out of a backpack and print a chemical sensor or other electronics they need, directly on the skin. It would be like a ‘Swiss Army knife’ of the future with everything they need all in one portable 3D printing tool.”

The researchers also successfully printed biological cells on the skin wound of a mouse. The technique could lead to new medical treatments for wound healing and direct printing of grafts for skin disorders.

One of the key innovations of their 3D printing technique is that the printer can adjust to small movements of the body during printing. Temporary markers are placed on the skin and the skin is scanned. The printer uses computer vision to adjust to movements in real-time.

“No matter how hard anyone would try to stay still when using the printer on the skin, a person moves slightly and every hand is different,” Prof McAlpine explained. “This printer can track the hand using the markers and adjust in real-time to the movements and contours of the hand, so printing of the electronics keeps its circuit shape.”

Another unique feature of this technique is that it uses a specialised ink made of silver flakes that can cure and conduct at room temperature. This is different from other 3D printing inks that need to cure at high temperatures and would burn the hand.

To remove the electronics, the person can simply peel off the electronic device with tweezers or wash it off with water.

“I’m fascinated by the idea of printing electronics or cells directly on the skin,” Prof McAlpine said. “It is such a simple idea and has unlimited potential for important applications in the future.”