Wednesday, January 01, 2003

91. Fingers With Force

Engineers at the University of Washington and Stanford University have developed a bed of tiny fingers made of silicon and polymer that can push objects around. "Each actuator is very simple," says Karl Böhringer, the University of Washington professor of electrical engineering who led the effort, "but together they can move objects much larger than themselves."
    Böhringer and his colleagues were trying to devise the best way to dock tiny satellites at a space station. NASA is betting that swarms of coffee-cup-size satellites will be able to perform mundane service functions more efficiently than space-suited astronauts. However, they'd need frequent refueling, and that would require a docking system that is small and lightweight.
    Böhringer already had the solution: "I'd been working on a way to move sheets of paper through a copying machine with a very thin mechanism." His concept was a paper feeder employing tiny fingers of silicon. In frictionless space, Böhringer realized, small satellites would be as easy to push around as paper. So he and his colleagues fabricated patches of fingers, each less than half an inch long, and threaded them together with tungsten wires. When the wires are charged with electric current, the normally curled fingers straighten out; straightened and curled in the right order, the fingers can maneuver a lightweight object into any position.
    Böhringer's silicon fingers could even have earthly applications. He imagines that such fingers could be put to work positioning minute objects, such as samples under a microscope.
— Jeffrey Winters

85. Robots That Rescue

When a person is trapped in a collapsed building, every second counts. But human rescuers often can't just rush in. "For a confined space below ground level, you need to get a structural engineer to certify it, get roped up, and get a rapid-extraction team ready," says Robin Murphy, director of the Center for Robot-Assisted Search and Rescue at the University of South Florida in Tampa. "You lose an hour and a half right there."
    Murphy has a better solution: rescue robots—some as small as a shoebox. They can be deployed almost immediately to find, treat, and help extract people trapped in rubble after an earthquake or explosion. Seven of the center's robots searched the rubble of the World Trade Center in the days after the September 11 attacks. "With a robot," she says, "you just throw it in."
    Rescue robots don't have minds of their own. Human operators outside the danger zone guide them, watching video from tiny cameras to look for victims. Some robots are now ready to be airlifted to a disaster area with a few hours' notice. The center's robots were deployed at the World Trade Center on the morning of September 12 in what proved to be a futile search for survivors.
    "If there's one problem, it's interpreting the images," Murphy says. "The robots passed by two sets of remains, and they weren't discovered until we reviewed the videotapes. Everything is covered in dust, so it's like looking at people in Pompeii."
    Based on the experience at Ground Zero, Murphy's lab is adapting the rescue robots to help operators more quickly differentiate survivors from victims. Murphy and her colleagues tested several sensors last August that measure things like carbon dioxide and body heat. The sensors were so effective that they could detect vital signs even through a biohazard suit—a necessity in the aftermath of a chemical or biological attack.
— Jeffrey Winters

92. Microwaves Might Be Good for You

If you're hoping the loudmouth on the cell phone next to you will get a brain tumor, you're likely to be disappointed. If he were a worm, he'd just grow and multiply. David de Pomerai, a molecular toxicologist at the University of Nottingham in England, put nematodes in an incubator and exposed them for 20 hours to a microwave field similar to that emitted by a mobile phone. "We were rather surprised to find that more of them were producing eggs," says de Pomerai. The irradiated worms also grew 10 percent longer than their unexposed, aluminum-foil-protected peers. This is the first study to show that microwaves can have an effect on living organisms other than just heating them up. (De Pomerai controlled heat as a factor in the experiment by keeping all the worms at an even 77 degrees Fahrenheit.)
    De Pomerai guesses that the worms' cells, when stressed by microwaves, probably produce proteins that repair damage and protect them. But until he understands how the cells are stressed in the first place, he won't know much: "We frankly don't have a clue as to how much microwave radiation is needed to cause irreversible damage to cellular proteins. Small to modest amounts of exposure may actually be a good thing, like red wine."
— Michael Abrams 

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