Lisa Zyga, Physorg.com:

The basis of the 2×4-inch “Digital Tattoo
Interface” is a Bluetooth device made of thin, flexible silicon and
silicone. It´s inserted through a small incision as a tightly rolled
tube, and then it unfurls beneath the skin to align between skin and
muscle. Through the same incision, two small tubes on the device are
attached to an artery and a vein to allow the blood to flow to a
coin-sized blood fuel cell that converts glucose and oxygen to
electricity. After blood flows in from the artery to the fuel cell, it
flows out again through the vein.

On both the top and bottom
surfaces of the display is a matching matrix of field-producing pixels.
The top surface also enables touch-screen control through the skin.

Thanks for a very creepy link, Josh.