The basis of the 2x4-inch "Digital Tattoo Interface" is a Bluetooth device made of thin, flexible silicon and silicone. Itīs 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. Instead of ink, the display uses tiny microscopic spheres, somewhat similar to tattoo ink. A field-sensitive material in the spheres changes their color from clear to black, aligned with the matrix fields.