Stanford engineers create a tiny, wirelessly powered cardiac device

A team of engineers at Stanford has demonstrated the feasibility of a super-small, implantable cardiac device that gets its power not from batteries, but from radio waves transmitted from outside the body. The implanted device is contained in a cube just eight-tenths of a millimeter in radius. It could fit on the head of pin.
In their paper, the researchers demonstrated wireless power transfer to a millimeter-sized device implanted five centimetres inside the chest on the surface of the heart