Researchers are teaching insects how to drive. This can lead to a wheelchair that can be controlled by twitching a muscle or two
AT FIRST glance, nothing seems wrong or extraordinary about the toy car that zips around Jeff Bloomquist's lab at University of Washington, USA. But when you look closer, you find the oddity: tied to a small bloom that juts like a bowsprit from the front of the car is a cockroach. Bloomquist, an insect neurophysiologist at Virginia Tech, and Steven Bathiche, a bioengineering graduate student at the University of Washington, are trying to harness the neuromascular reactions of insects to model cars. Interesting, but to what end? The duo hope to scale up the concept and develop a wheelchair that handicapped people could control with the electrical impulses generated by the twitch of a facial muscle.
In their experiment, the researchers attach an electrode to the muscles the cockroach uses for flying. When the researchers blow air on the cockroach, the slight breeze and the insect's unsupported feet make the cockroach think it is flying, so it starts moving its wing muscles. The electrode reads the electric signals the muscles make when they contract and sends them to a microprocessor on the car, which starts the motor. "The first time we made it work, the thing went blasting down the hall," Bloomquist recalls. "The movement generates a breeze that rein-forces the flight behaviour, so it flies for a longtime."
However, the cockroach-driven model has some drawbacks. "Cockroaches only fly in short hops, and they don't steer well," says Bathiche. So he now uses hawkmoths. "They are much more elegant fliers. They are one of the fastest insects in the world, and the thing that's really nice is when they want to turn, they lean in the opposite direction."
Bathiche made a harness that measures how the moth shifts its weight when turning and uses that signal to steer the car in the direction the moth wants to go. He has also fine-tuned the microprocessor so that the speed of the car varies. When the moth wants to speed up, it beats its wings faster; Bathiche1 s microprocessor detects the change and accelerates the car.
Bloomquist and Bathiche do not anticipate any significant problems in developing a muscle-controlled wheel-chair. Human muscles are so big that they generate relatively large electric signals just from tensing slightly, says Bloomquist. In fact, the researchers say human trials probably will not require any more intermediate steps. "Feedback from the experimentee is going to be very important to set up a system like this," says Bathiche. "You can't talk to a paraplegic dog and ask it if it works."
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