Soon, insect-like robots that crawl into creeks and carry heavy loads

WASHINGTON - An insect-like robot with hundreds of tiny legs could soon crawl through cracks to explore collapsed structures, collect environmental samples and do other tasks where its small size is a benefit.

The past few years have given rise to a growing number of microrobots, miniaturized mobile machines designed to perform specific tasks.

But researchers at the UW and Stanford University new discovery have taken these microrobots a step further by creating pint-sized robots that carry heavy loads-more than seven times its own weight-and move in any direction.

Karl Bohringer, a University of Washington professor of electrical engineering, is the lead author of the study describing the miniature robot that weighs half a gram (roughly one-hundredth of an ounce), measures about 1 inch long by a third of an inch wide, and is about the thickness of a fingernail.

Technically it is a centipede, with 512 feet arranged in 128 sets of four.

Each foot consists of an electrical wire sandwiched between two different materials, one of which expands under heat more than the other.

A current travelling through the wire heats the two materials and one side expands, making the foot curl.

Rows of feet shuffle along in this way at 20 to 30 times each second.

“The response time is an interesting point about these tiny devices. On your stove, it might take minutes or even tens of minutes to heat something up. But on the small scale it happens much, much faster,” said Bohringer.

The legs’ surface area is so large compared to their volume that they can heat up or cool down in just 20 milliseconds.

“It’s one of the strongest actuators that you can get at the small scale, and it has one of the largest ranges of motion. That’s difficult to achieve at the small scale,” said Bohringer.

The microchip, the robot’s body and feet, was first built in the mid 1990s at Stanford University as a prototype part for a paper-thin scanner or printer.

And now, the researchers have flipped it over so the structures that acted like moving cilia are on the bottom, turning the chip into an insectlike robot.

“There were questions about the strength of the actuators. Will they be able to support the weight of the device? We were surprised how strong they were. For these things that look fragile, it’s quite amazing,” said Bohringer.

The tiny legs can move more than just the device.

Researchers could pile paper clips onto the robot’s back until it was carrying more than seven times its own weight.

This means that the robot could carry a battery and a circuit board, which would make it fully independent.

Limbs pointing in four directions allow the robot flexibility of movement.

However, Bohringer added that as with other devices of this type, a major challenge is the power supply-a battery would only let the robot run for 10 minutes, while researchers would like it to go for days.

Another is speed-right now the UW robot moves at about 3 feet per hour-and it’s far from the slowest in the microrobot pack.

The study is published in the June issue of the Journal of Microelectromechanical Systems. (ANI)