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TR10: Biological Machines

Michel Maharbiz’s novel interfaces between machines and living systems could give rise to a new generation of cyborg devices.
February 24, 2009
Cyborg beetle: By equipping a giant flower beetle with a processor and implanting electrodes that deliver electrical jolts to its brain and to its wing muscles, scientists have created a living machine whose flight can be wirelessly controlled.Cyborg beetle: By equipping a giant flower beetle with a processor and implanting electrodes that deliver electrical jolts to its brain and to its wing muscles, scientists have created a living machine whose flight can be wirelessly controlled.
Cyborg beetle: By equipping a giant flower beetle with a processor and implanting electrodes that deliver electrical jolts to its brain and to its wing muscles, scientists have created a living machine whose flight can be wirelessly controlled.John Burgoyne

A giant flower beetle flies about, veering up and down, left and right. But the insect isn’t a pest, and it isn’t steering its own path. An implanted receiver, microcontroller, microbattery, and six carefully placed electrodes–a payload smaller than a dime and weighing less than a stick of gum–allow an engineer to control the bug wirelessly. By remotely delivering jolts of electricity to its brain and wing muscles, the engineer can make the cyborg beetle take off, turn, or stop midflight.

The beetle’s creator, Michel ­Maharbiz, hopes that his bugs will one day carry sensors or other devices to locations not easily accessible to humans or the terrestrial robots used in search-and-rescue missions. The devices are cheap: materials cost as little as five dollars, and the electronics are easy to build with mostly off-the-shelf components. “They can fly into tiny cracks and could be fitted with heat sensors designed to find injured survivors,” says Maharbiz, an assistant professor at the University of California, Berkeley. “You cannot do that now with completely synthetic systems.”

Maharbiz’s specialty is designing interfaces between machines and living systems, from individual cells to entire organisms. His goal is to create novel “biological machines” that take advantage of living cells’ capacity for extremely low-energy yet exquisitely precise movement, communication, and computation. Maharbi­z envisions devices that can collect, manipulate, store, and act on information from their environments. Tissue for replacing damaged organs might be an example, or tables that can repair themselves or reconfigure their shapes on the basis of environmental cues. In 100 years, Maharbiz says, “I bet this kind of machine will be everywhere, derived from cells but completely engineered.”

The remote-controlled beetles are an early success story. Beetles integrate visual, mechanical, and chemical information to control flight, all using a modicum of energy–a feat that’s almost impossible to reproduce from scratch. In order to deploy a beetle as a useful and sophisticated tool like a search-and-rescue “robot,” Maharbiz’s team had to create input and output mechanisms that could efficiently communicate with and control the insect’s nervous system. Such interfaces are now possible thanks to advances in microfabrication techniques, the availability of ever smaller power sources, and the growing sophistication of microelectromechanical systems (MEMS)–tiny mechanical devices that can be assembled to make things like radios and microcontrollers.

Stuck to the beetle’s back is a commercial radio receiver atop a ­custom-made circuit board. Six electrode stimulators snake from the circuit board into the insect’s optic lobes, brain, and left and right basilar flight muscles. A transmitter attached to a laptop running custom software sends messages to the receiver, delivering small electric pulses to the optic lobes to initiate flight and to the left or right flight muscle to trigger a turn. Because the receiver sends very high-level instructions to the beetle’s nervous system, it can simply signal the beginning and end of a flight, rather than sending continuous messages to keep the beetle flying.

Others have created interfaces that make it possible to remotely control the movements of rats and other animals. But insects are much smaller, and thus more challenging. Maharbiz is one of the few scientists with a sufficiently deep knowledge of both biology and engineering to successfully mesh an animal’s nervous system with MEMS technologies. His team previously modified ­beetles during the pupal stage, so that their implants are invisible in adulthood–a valuable property if they are to be used in covert missions. The researchers are now working on novel microstimulators and MEMS radio receivers that will allow for more precise neural targeting and even smaller systems.

The cyborg beetle is just one of an array of new technologies incubating in ­Maharbiz’s lab, including microflui­dic chips that can deliver controlled amounts of oxygen and other chemicals–even DNA–to individual cells. This kind of system could be used to precisely control the development of cell populations. Ultimately, Maharbiz wants to develop programmable cell-based materials, like those required for the fantastical self-healing table. For now, his team focuses on finding the best ways to manipulate devices such as the beetles. “We want to find out,” says Maharbiz, “what are the limits of control?”