Imagine a robot so small and so flexible and so clever that it could be injected into your bloodstream to scour your vessels and search for problems.
Scientists and engineers at Tufts University say they are well on the road to creating a wide range of devices -- called "soft-bodied robots" -- that can do just that, as well as many other chores. And guess where they got their inspiration? From one of the most amazing creatures on the planet: the caterpillar.
"The caterpillar doesn't have any bones, it doesn't have any joints, and yet it can move in very flexible, complex ways," says Barry Trimmer, a neurobiologist at Tufts. "But its brain isn't very complicated. There aren't many neurons in there."
Trimmer and David Kaplan, professor of biomedical engineering, are co-directors of a multidisciplinary project at Tufts, funded chiefly by the W.M. Keck Foundation. The purpose of the project is to create robots that are radically different from the awkward mechanical robots seen today.
"You don't see robots that are like animals that can collapse down and are soft and pliable," Trimmer says. "There are things that animals can do that robots can't, and we'd like to exploit that."
The researchers already have a few robots "crawling around the floor" of their lab, but they are at least 18 months away from introducing any of them to the public. First, they want a soft-bodied robot that can move horizontally and climb up a twig. That in itself would be a remarkable achievement, but it would only be the beginning.
Some day, they say, we should see robots of all sizes, from tiny to gargantuan, that can carry out tasks that are too risky for humans. They will be so cheap to build that they will be expendable, and they will play key roles in everything from medicine to space exploration. And it's all because of the talents of the common caterpillar.
Ambitious goals, to be sure, and it sounds like science fiction, but the members of the Tufts team are deadly serious.
"This started to come together as people in engineering and biology and biomedical engineering started talking to one another," says Trimmer. That's a significant accomplishment because engineers and scientists don't always speak the same language.
Trimmer's contribution to the effort grew out of nearly 20 years of research on the caterpillar.
"I became specialized in this particular animal because the caterpillar has lots of technical advantages," he says. "You can take his brain out and keep it alive, so you can study things in isolation."
Trimmer says it wasn't easy in the beginning to get engineers interested.
"When you tell engineers that you want to make something that's completely flexible and can move in any direction, they look at you like you're crazy," he says. He adds that it would require a supercomputer and a complex control system to operate a hard-bodied robot like a caterpillar, if it could be done at all.
The engineers and scientists came together when Trimmer told his colleagues that he knows how a caterpillar does it.
The key, he told them, is that the caterpillar's body is made of "smart material," a term familiar to engineers. Smart material has its function built in, so it doesn't take much brain power to make it do its thing, like a foam mattress that always returns to its original shape. Some smart materials change shape when a modest electric current is applied. The material, like the outer skin of a caterpillar, "knows" what it's supposed to do.
Thus robots, based on biological models, wouldn't need a complex control system, because the function would be encoded in the tissues of the robot. Like the caterpillar, a tiny "brain" could run the show.
The first synthetic caterpillar will look pretty much like an overgrown caterpillar, Trimmer says. But it should be easy to scale it down to a size so small it could work inside the human body, flexing its way through blood vessels, or even into the lungs, says Trimmer.
During its lifetime, a caterpillar increases its body mass 10,000 fold, Trimmer says.
"If we use the same principles to build our robots we'll be able to scale them up or down, make them small or very big quite easily," he adds.
And if he's right, here's the best part. These little critters will be dirt cheap, because once all the bugs are sorted out, it won't take much to produce them.
"You could make them disposable," Trimmer says. "You could compress a bunch of robots into a canister, and shoot them into a mine field. The canister breaks open, all these little critters crawl out and go off in different directions. When they find a mine, they send out a signal. You don't care if they get blown up because they don't cost $100,000 each. They cost 50 cents."
Maybe so, but it's hard to believe the Tufts team can come even close to matching the marvels of the caterpillar.
The caterpillar is one of the most successful animals on the planet. It's found on nearly every tree in the world, Trimmer says. And at the end of its life it turns into a moth.
"That's like a PC suddenly turning into a Macintosh," Trimmer says.
And the amazing thing is the caterpillar, and the moth it becomes, have the same set of genes. Somewhere along the way, the caterpillar rewires its own system.
"It keeps the same neurons," Trimmer says, "but they do a different job in the moth than they do in the caterpillar. That's remarkable because it must know what it's supposed to be in two different life stages. That never ceases to amaze me."
So it's quite possible that the Tufts team will learn some astonishing things from the caterpillar. But surpass it? Not likely.