All spiders can produce silk — a material that is a sixth of the size of a human hair — that they use to capture prey, protect offspring, reproduce and build shelter for themselves.

Xinwei Wang, associate professor of mechanical engineering, looked past the reputation of people’s least favorite eight-legged houseguest to do research on the ability of spider silk to conduct heat.

“Spider silk came to our attention because mechanically it is very strong, it is stretchable and little is known about its thermal transport capability,” Wang said. “Also we have some very unique technologies that can measure the thermal conductivity and specific heat of micro wires. So we bought spiders, put them in cages and fed them and collected the silks they produced for our research.”

The research that began in September 2010 and was partially funded by the Army Research Office and the National Science Foundation resulted in the discovery that the silk of golden silk orbweavers can transfer heat very effectively.

Along with post-doctoral research associate Xiaopeng Huang and doctoral student Guoqing Liu, Wang made the discovery that could change the way scientists think about the thermal conducting ability of organic material. The spider silk research team is optimistic about its work with the microscopic material and has found great potential in its small package.  

“In the novel, ‘The Godfather,’ it is said that, ‘Behind every great fortune, there is a crime,’ so instead, for my research, it is ‘Behind every tiny material, there is a secret,’” Liu said.

While all sorts of things are able to transfer heat, metals are the main material that is used for its natural conductivity capabilities. The conductivity of most materials diminishes as it is stretched, but that was not the case with spider silk, as Wang and his research team discovered.

As an organic material that was stretchy, spider silk would be thought to have relatively low potential for conducting heat, but when the spider silk was stretched, its ability to transfer heat actually increased. When stretched, the silk was able to conduct heat better than copper, a metal that is one of the best thermal conductors.

“These kinds of materials are always sought in electronics for heat dissipation, in bio-medical applications for therapy and device enclosure and in energy areas as light weight materials to meet the demand of heat dissipation,” Wang said.

Wang is optimistic that this discovery will lead to new ideas for material design and in cooperation with other research can lead to mass production techniques.

Wang and his research team — whose article “New Secrets of Spider Silk: Exceptionally High Thermal Conductivity and its Abnormal Change under Stretching” was recently published by the weekly materials science journal Advanced Materials — look forward to delving deeper into the potential of spider silk by looking at how different spider species and types of silk affect spider silk’s ability to transfer heat.

However, many hurdles exist for future research because of the vast variety of spider species and the fact that a spider can produce many different kinds of silk in its lifetime due to factors like health, age and environment.

“Future research will be very time-consuming and challenging,” Wang said. “But we like it and will manage to overcome the challenges.”