A very tiny flying machine by Kevin Ma et.al. at Harvard. A summary and the paper appears in Science.
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A new fabrication process based on the principle of pop-up books made this microrobot possible, but don't expect to see it in stores any time soon. It takes 2 days to make a single RoboBee, and the tiny device still requires a tether to supply power and guidance for flight. "Getting all the sensors and power on board is definitely many years out," says Sarah Bergbreiter, a mechanical engineer at the University of Maryland, College Park, who was not involved in the work. Nonetheless, this new robot is "pretty fantastically cool," she adds.
Although thousands of insect species dart about with agility that puts stunt pilots to shame, most engineers have considered building a robotic fly an impossible task. You can't buy off-the-shelf parts for the body, and no existing power source, sensors, or controllers are small enough to fit on board. What's more, researchers don't even have a good grasp on how aerodynamic principles change on such small scales, so they can't precisely predict how delicate wing movements will alter flight. Yet 12 years ago, mechanical engineer Robert Wood, who is now at Harvard University, decided to embrace the challenge of building an insect-sized robot—in part to understand the flight mechanics of small flapping wings, and in part "because it was so hard," he recalls.
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