By Ketul PatelThe Daily Northwestern

Whiskers are no longer strictly a cat-and-mouse game.

Mitra Hartmann, a professor of biomedical engineering, and Joseph SoloMonday, a third-year graduate student, have designed robotic whiskers made of thin wires which rotate or “whisk,” mimicking rats’ movement. Using the concept of torque, they can determine where the wires bend when touching an object and form a three-dimensional picture of it. They presented their findings in the Oct. 5 issue of Nature, an international scientific journal.

Several species of mammals, including rats, use whiskers to navigate and build a mental image of their surroundings. Rats whisk, or rotate, their whiskers to get a sense of the topography and texture of their environment.

NU’s robotic whiskers differed from similar inventions, Hartmann said.

“Some whiskers are glorified bump detectors because they merely tell you that the wire has been touched,” Hartmann said.

Sensory receptors in a rat whisker measure the direction and intensity of the bend when it hits an object. The rat’s brain uses the information to form a three-dimensional image. The robotic whiskers form images by using strain gauges to measure how much the wire bends.

The whiskers can be used in practical situations like assembly lines, pipelines and on underwater vehicles. But Hartmann emphasized that the whiskers have some limitations.

“We don’t see this as a replacement for cameras,” she said. “We see them as a complementary means of getting a sense of the world.”

Hartmann and Solomon swept wires of differing lengths over the head of a Chia Pet and downloaded the information to a computer program, which plotted the points to form a three-dimensional image, Solomon said.

“Each time a whisker touches an object, it collects more and more points,” he said. “We connected these points to form a three-dimensional image.”

Solomon said the image was “pretty accurate.” Because this equation worked well in forming the image, Solomon said he is fairly confident that the model can be used to describe how rats sense their environment.

“It is theoretically possible that a rat uses whiskers in the same way,” he said.

Hartmann said this discovery can have a variety of applications.

“It really does walk the line between biology and engineering,” she said. “We will be able to use this research in so many ways.”

Reach Ketul Patel at [email protected].