Electronic skin could be used for
many applications, including prosthetic devices, wearable health monitors,
robotics and virtual reality. A major challenge is transferring ultrathin
electrical circuits onto complex 3D surfaces and then having the electronics be
bendable and stretchable enough to allow movement. Some scientists have
developed flexible electronic tattoos for this purpose, but their production is
typically slow, expensive and requires clean-room fabrication methods such as
photolithography. Researchers patterned a circuit template onto a sheet of
transfer tattoo paper with an ordinary desktop laser printer.
They then coated the template
with silver paste, which adhered only to the printed toner ink. On top of the
silver paste, the team deposited a gallium-indium liquid metal alloy that
increased the electrical conductivity and flexibility of the circuit. Finally,
they added external electronics, such as microchips, with a conductive glue
made of vertically aligned magnetic particles embedded in a polyvinyl alcohol
gel. They transferred the electronic tattoo to various objects and demonstrated
several applications of the new method, such as controlling a robot prosthetic
arm, monitoring human skeletal muscle activity and incorporating proximity
sensors into a 3D model of a hand.
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