There are a host of theories about how to power a PC network located on a person. Initial efforts like MIThril weave electronic circuitry directly into clothing. But since it doesn't require a lot of current to send information from, say, a camera in a pocket to a microprocessor in a collar button, the natural conductivity of the skin is considered a good alternative to more traditional wiring. Some piece of the body network, however, would need to touch your skin at all times. With normal movements, that could be impossible. "We were never able to get around that," says Daniel Russell, senior manager at IBM's Almaden Research Center. "We stopped working on it."
Russell believes that a low-power wireless connection is the best option -- something that IBM recently demonstrated when it successfully powered a handheld cellphone with a battery the size of a grain of rice, hidden in an earring.
Display problems need to be tackled as well. The first wearable computers use head-mounted displays that are uncomfortable, bulky and silly looking, instead of slick and almost invisible. The next evolution of head-mounts is expected to be a huge leap forward, likely using a laser display that paints the image directly onto the retina. A tiny device that sits in front of one eye projects the text or graphics through the wearer's pupil, arranging the pixels in a raster pattern on the retina. This does not obscure the view but merely superimposes material over it. The result is a very high-resolution image with adjustable contrast ratio and luminance. The low-intensity display uses very little power, so it will not harm the eye and can be quite small.
But anyone wearing a head-mounted display is not likely to be inconspicuous. And that means a lot of people probably won't wear them -- unless they become the next rage. Predicting fashion, researchers hope, is not a precise science. "When the Walkman came out," says IBM's Russell, "people said nobody would wear them in public. Yet 200 years ago, men wore white powder wigs and silk stockings. I have no idea what people will wear. And neither does anyone else."
That notion notwithstanding, developers hope by the end of the decade to get rid of the head-mount altogether and embed the display apparatus in a normal-looking pair of glasses.