This image shows an electronic circuit printed directly onto skin using a customised version of a cheap 3D printer.
The technique, developed by researchers at the University of Minnesota in the US and described in the journal Advanced Materials, relies on machine vision to track tiny movements in the hand, and makes circuits with a silver-based ink that works at room temperature.
The researchers says 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.
As well as circuits, 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.