Power/Performance Bits: April 1

Heat-conducting polymer
Polymer materials are usually thermal insulators but according to a team researchers including the Georgia Institute of Technology, University of Texas at Austin, and the Raytheon Company, by harnessing an electropolymerization process to produce aligned arrays of polymer nanofibers, they’ve developed a thermal interface material able to conduct heat 20 times better than the original polymer and can reliably operate at temperatures of up to 200 degrees Celsius.

This scanning electron microscope image shows vertical polythiophene nanofiber arrays grown on a metal substrate. The arrays contained either solid fibers or hollow tubes, depending on the diameter of the pores used to grow them. (Source: Virendra Singh/Georgia Tech)

They explained that the new thermal interface material could be used to draw heat away from electronic devices in servers, automobiles, high-brightness LEDs and certain mobile devices. The material is fabricated on heat sinks and heat spreaders and adheres well to devices, potentially avoiding the reliability challenges caused by differential expansion in other thermally-conducting materials.

‘Living’ materials
MIT engineers have coaxed bacterial cells to produce biofilms that can incorporate nonliving materials, such as gold nanoparticles and quantum dots after they were inspired by natural materials such as bone — a matrix of minerals and other substances, including living cells.

The engineers said these “living materials” combine the advantages of live cells, which respond to their environment, produce complex biological molecules, and span multiple length scales, with the benefits of nonliving materials, which add functions such as conducting electricity or emitting light. The materials represent a simple demonstration of the power of this approach, which could one day be used to design more complex devices such as solar cells, self-healing materials, or diagnostic sensors.

Their idea was to put the living and the nonliving worlds together to make hybrid materials that have living cells in them and are functional — an interesting way of thinking about materials synthesis, and is very different from what people do now, which is usually a top-down approach.

An artist’s rendering of a bacterial cell engineered to produce amyloid nanofibers that incorporate particles such as quantum dots (red and green spheres) or gold nanoparticles.
(Source: MIT)

These hybrid materials could be worth exploring for use in energy applications such as batteries and solar cells, the researchers added.