Smallest walking robot makes microscale measurements

The team's paper, "Magnetically Programmed Diffractive Robotics," published in Science.

"A walking robot that's small enough to interact with and shape light effectively takes a microscope's lens and puts it directly into the microworld," said Paul McEuen, professor of physical science emeritus, who led the team. "It can perform up-close imaging in ways that a regular microscope never could."

Cornell scientists already hold the world's record for the world's smallest walking robot at 40-70 microns.

The new diffractive robots are "going to blow that record out of the water," said Itai Cohen, professor of physics and co-author of the study. "These robots are 5 microns to 2 microns. They're tiny. And we can get them to do whatever we want by controlling the magnetic fields driving their motions."

Diffractive robotics connects, for the first time, untethered robots with imaging techniques that depend on visible light diffraction -- the bending of a light wave when it passes through an opening or around something. The imaging technique requires an opening of a size comparable to the light's wavelength. For the optics to work, the robots must be on that scale, and for the robots to reach targets to image, they have to be able to move on their own. The Cornell team has achieved both objectives.

Controlled by magnets making a pinching motion, the robots can inch-worm forward on a solid surface. They can also "swim" through fluids using the same motion.

The combination of maneuverability, flexibility and sub-diffractive optical technology create a significant advance in the field of robotics, the researchers said.

The research was made possible by the Cornell Center for Materials Research, the National Science Foundation and the Cornell NanoScale Science and Technology Facility.