The data encoding these words was carried as pulses of light on its journey from my computer to yours. But, as new research demonstrates, using light to carry encoded alphanumeric messages over long distances doesn’t require computers, optical fiber, or even electricity.
By patterning flammable metallic salts on a nitrocellulose fuse, researchers at Harvard and Tufts University have encoded messages that can be transmitted without the need for a power source. When one fuse burns, the metallic salts along its length emit pulses of infrared and visible light of different colors whose sequence encodes, “LOOK MOM NO ELECTRICITY.” The system, described today in the journal Proceedings of the National Academy of Sciences, is inspired by chemical information storage in biological cells.
David Walt, professor of chemistry at Tufts and Harvard’s George Whitesides developed the infofuses in response to a call from the Defense Advanced Research Projects Agency (DARPA) for technologies to allow soldiers stranded without a power source to communicate. DARPA wanted “something that doesn’t require any electronics or heavy equipment to lug around,” says Walt.
Civilians stranded in a mountainous area without cell reception could use the infofuses, too, Walt says. His cell phone dropped our call a moment later. When he called back, I suggested maybe he needed an infofuse now. “That’s the problem–it doesn’t work over three thousand miles,” he says. The group is now working on extending the range of the optics used to read the signal, which can currently be read from 600 meters away in bright ambient light using a CCD camera; Walt says 1.5 kilometers should be possible using the current optics. “We’re [also] trying to figure out a way to dynamically encode a message on the fly in the field without specialized equipment,” says Walt. So far they’ve used micropipetters and ink-jet printers to pattern the fuses.
Another cool technology recently pioneered by Whitesides is paper medical diagnostics.