Researchers at the National Institute of Advanced Industrial Science and Technology near Tokyo have created the first micromechanical device with living components incorporated into them.
Nanobiotechnologist Yuichi Hiratsuka, now at the University of Tokyo, and his colleagues, have built a microscopic motor powered by bacteria.
The bacterium used in the device, Mycoplasma mobile is one of nature’s fastest moving microbes; it is able to glide over surfaces at speeds of up to seven-tenths of an inch per hour, the equivalent of a person moving at 20 miles per hour.
Hiratsuka and his team etched circular tracks, coated with glycoproteins, into tiny cogs. M. mobile needs these sugary proteins to adhere to a surface. The bacteria were genetically engineered, and coated with vitamin B7, to make them more adhesive. A rotor (left) was then added to the device, so that it moved when the bacteria slid along the pathways on the cog, which can hold 100 bacteria. The researchers were able to place 20,000 such rotors onto the surface of a silicon chip, with each cog rotating at an average of 2 revolutions per minute:
The system can repair itself and needs only glucose as a source of fuel. It contains no wires and, unlike electronic motors, can work in a wet environment. The system could be improved by adding more bacteria to the cogs.
“We would like to make micro-robots driven by biological motors,” says Hiratsuka, adding that “we may be able to construct electronic generator systems, which generate electric energy from an abundant chemical source – glucose in the body”.
The microbe-powered motor may possibly be used to propel micropumps, perhaps like the one developed by researchers at the University of Washington.
Alexander Mamishev, an associate professor of electrical engineering, led a team which has developed a microscopic ion pump small enough to fit on a silicon chip. The device uses an electrical charge to produce a jet of air on the surface of the chip.
The ion pump consists of two basic components, an emitter and a collector. The emitter, which has a diameter of 2 micrometers, generates ions, which travel along an electrical field to the collector, creating a cool jet of air that cools the chip surface. The infrared images on the right show the changes in surface temerature of a chip when the pump is switched off (top) and on (bottom).
“With this pump, we are able to integrate the entire cooling system right onto a chip,” says Mamishev. “That allows for cooling in applications and spaces where it just wasn’t realistic to do before.”
The University of Washington researchers, together with collaborators from Kronos Advanced Technologies and Intel, have received a $100,000 grant from the Washington Technology Center to take the project into the second phase.
The ultimate aim of the project is to develop cooling systems which can be built into the next generation of microchips and microelectromechanical devices. Researchers involved in the work are looking into incorporating carbon nanotubes and other nano-structures to improve the performance of the ion pumps.
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