Robotic Venus flytrap snaps at electronic flies
Researchers designing agile robots generally look to agile animals, such as cockroaches and sharks, for ideas. Now a fast-moving robot has been created from an unlikely source of inspiration: a plant.
The plant is the carnivorous Venus flytrap, which catches its own dinner. Like the real flytrap, the synthetic flytrap can snatch objects flitting through the air and hold them tight between its “jaws.” And like the real thing, the laboratory version can discriminate between different kinds of “prey.”
“Of course the Venus flytrap is smarter and more advanced in all ways” than the new device says Arri Priimägi of Finland’s Tampere University of Technology, a member of the team that built the artificial flytrap. Still, he says, his team’s creation “can grip objects. We can move them in a very controlled manner from one place to another, and the weight of the object can be hundreds of times higher” than the weight of the robot.
Compared with the fringed and luridly colored natural flytrap, the new Finnish flytrap is plain. It has a “gripper” made of a rubbery material sensitive to light. At rest, the gripper, which is less than an inch long, looks like the horizontal bar of a capital T. The T’s vertical column is formed by a slender cable that transmits light, giving the gripper its own headlight.
A bright object — a grain of sugar, say, or a scrap of foil — reflects this light as a mirror would. When enough reflected light hits the gripper, its ends bend up into a U shape, capturing the bright object. An object that doesn’t reflect much light, on the other hand, is allowed to fly on by.
The gripper can close in a fifth of a second, roughly half as fast as the Venus flytraps lobes clamp shut on a fly, the team reports in this week’s Nature Communications. If the researchers turn off the light, their flytrap releases its prey, unlike the living Venus flytrap, which “just digests the object, “Priimägi points out.
Soft robots like the Finnish flytrap are not uncommon, but Priimägi calls the device a “breakthrough” because it’s spurred to action by light signals from its surroundings. This could be “a step toward intelligent micro-robotics,” he says. A similar system might be used to gather defective items off an assembly line, for example.
One scientist who has studied the mechanics of the greener, meaner living flytrap scoffs at the imitation. The real thing, says Alexander Volkov of Oakwood University in Huntsville, Ala., needs much less energy to close and has a form of memory.
Priimägi says his team’s flytrap has yet to be perfected, and while it will never be as sophisticated as the plant version, it will get better. “There is an evolution of millions of years behind the Venus flytrap,” he says. “In our case, there is an evolution of six months. … There are many things we can change.”