Oct. 18, 2005— A display implanted under the skin and run by robots the size of dust motes could be the next best thing for checking your heart rate or cholesterol.

The dermal display, still a theoretical idea based on fact, is being worked on by Robert A. Freitas, Jr., a senior research fellow at the Institute for Molecular Manufacturing in Palo Alto, Calif.

The display would consist of billions of light-emitting robots implanted under the skin and capable of rearranging themselves to spell out words and numbers and produce animations.

They would display data received from other nanobots in the body designed to monitor a person's vital signs. Instructions from the patient could be communicated by touch-screen-like finger taps on the skin.

"There's a saying that goes, 'If you forecast the future and it sounds like science fiction it might be wrong. If you forecast the future and it doesn't sound like science fiction, it's definitely wrong,'" said professor Ralph Merkle, an expert in nanotechnology at the Georgia Institute for Technology.

The idea comes from Freitas' work writing the "Nanomedicine" book series. In these books, he analyzes the plausibility of various nanorobotic medical systems.

The display relies on nanorobots that not only work to present the data but also collect it.

Billions of them would have to be stationed in tissues, bones, and blood throughout the body, where they would monitor various physiological parameters such as blood pressure and periodically communicate their findings to the nanorobots that make up the display.

The actual communication network would also be made up of the tiny robots.

Sitting about 200 to 300 microns below the surface of the skin, the display would consist of about three billion nanorobots that cover a rectangular area on the back of hand or the forearm about six by five centimeters.

The mote-sized machines would maintain their respective positions in a predetermined array and draw on local sources of oxygen and glucose for power.

When turned on, they would emit light through diode-like elements embedded in their surface. When turned off by the user, the skin would resume its natural color.

Not only could the dermal display be used for medical purposes, but it could also be used as an embedded PDA, MP3, or video player.

"It would never need to be recharged or have its batteries replaced because it draws power directly from the user's own natural glucose supplies, which sounds like a lot of fun," said Freitas.

Freitas has turned his attention to figuring out how to build the nanorobots. This will involve sophisticated methods for building tiny machines that can fabricate and assemble even tinier parts.

And once that is realized, said Freitas, he needs to find ways to mass manufacture the nanorobots cheaply and precisely.