Biomimetic-engineering design can replace spaghetti tangle of nanotubes in nove...( Nanoelectromechanical systems (NEMS)...)

Nanoelectromechanical systems (NEMS) devices have the potential to revolutionize the world of sensors: motion, chemical, temperature, etc. But taking electromechanical devices from the micro scale down to the nano requires finding a means to dissipate the heat output of this tiny gadgetry.

In a paper appearing in Nano Letters, Professor Markus Buehler and postdoctoral associate Zhiping Xu of MIT's Department of Civil and Environmental Engineering say the solution is to build these devices using a thermal material that naturally dissipates heat from the device's center through a hierarchical branched network of carbon nanotubes. The template for this thermal material's design is a living cell, specifically, the hierarchical protein networks that allow a cell's nucleus to communicate with the cell's outermost regions.

"The structure now used when designing materials with carbon nanotubes resembles spaghetti," said Buehler, who studies protein-based materials at the nano and atomistic scales with the goal of using biomimetic-engineering principles to design human-made materials. "We show that a precise arrangement of carbon nanotubes similar to those found in the cytoskeleton of cells will create a thermal material that effectively dissipates heat, which could prevent a NEMS device from failing or melting."

NEMS devices are characterized by extremely small, high-density heat sources that can't be cooled by traditional means. Even the microelectromechanical systems (MEMS) devices used in automobiles and electronics are hard to cool, because conventional thermal management strategies such as fans, fluids, pastes and wiring often don't work at these small scales; heat buildup in MEMS frequently leads to catastrophic device failure, which limits the reliability of larger systems.

But the number of heat-conducting fibers or carbon nanotubes (CNTs) that can be connected to the heat source at the center of a NEMS device is l
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