In an astonishing discovery Xinwei Wang, an associate professor of mechanical engineering at Iowa State University found spider silk to be a top quality carrier of heat.

Wang said, “This is very surprising because spider silk is organic material. For organic material, this is the highest ever. There are only a few materials higher – silver and diamond.”

Usually and most commonly we move heat by heating water, piping it somewhere to use it for a purpose.  Spider silk has been and is still in research for its strength and ways to produce it at scale.  Now there is another motivator and huge potential markets.

Wang work is the study of thermal conductivity, the ability of materials to conduct heat. He’s been looking for organic materials that can effectively transfer heat. It’s something most materials from living things aren’t very good at all.  The best are diamonds, copper and aluminum that are very good, the very best, diamonds and silver are quite expensive and hardly suitable for most uses.

Spider silk has some interesting properties: its very strong, very stretchy, only 4 microns thick (human hair is about 60 microns).  Until now no one had actually tested spider silk for its thermal conductivity.

Spider Silk Properties Diagram. Full details in the study paper linked below. Image courtesy Iowa State University.

Wang decided to try some lab experiments with Xiaopeng Huang, a post-doctoral research associate in mechanical engineering; and Guoqing Liu, a doctoral student in mechanical engineering, becoming a team to help with the project.

So he ordered eight spiders – Nephila clavipes, golden silk orbweavers – and put them to work eating crickets and spinning webs in the cages he set up in an Iowa State University greenhouse.  Wang and his research team found that spider silks – particularly the draglines that anchor webs in place – conduct heat better than most materials, including very good conductors such as silicon, aluminum and pure iron. Spider silk also conducts heat 1,000 times better than woven silkworm silk and 800 times better than other organic tissues.

The results have been published in the journal Advanced Materials, New Secrets of Spider Silk: Exceptionally High Thermal Conductivity and its Abnormal Change under Stretching.  The paper reports that using laboratory techniques developed by Wang, spider silk conducts heat at the rate of 416 watts per meter Kelvin.  That compares to copper at 401 – your skin measures 0.6.

Wang said, “I think we tried the right material. Our discoveries will revolutionize the conventional thought on the low thermal conductivity of biological materials. This takes time and patience. “

The research reveals a surprising attribute about spider silk; Wang explains that when spider silk is stretched, thermal conductivity also goes up. Wang said stretching spider silk to its 20 percent limit also increases conductivity by 20 percent. Most materials lose thermal conductivity when they’re stretched.  This is astonishing news.

Wang wrote in the study paper the discovery “opens a door for soft materials to be another option for thermal conductivity tuning.”  It could lead to spider silk helping to create flexible, heat-dissipating parts for electronics, better clothes for hot weather, bandages that don’t trap heat and many other everyday applications.

Wang’s expertise comes to fore with a high quality explanation in lay terms explaining the technology is all about the defect-free molecular structure of spider silk, including proteins that contain nanocrystals and the spring-shaped structures connecting the proteins. Wang suggests more research needs to be done to fully understand spider silk’s heat-conducting abilities.

Wang is also wondering if spider silk can be modified in ways that enhance its thermal conductivity. He said the researchers’ preliminary results are very promising.

For the university press release Wang marveled at what he’s learning about spider webs, everything from spider care to web unraveling techniques to the different silks within a single web.

“I’ve been doing thermal transport for many years,” Wang said. “This is the most exciting thing, what I’m doing right now.”

Just so Professor, for us too.  Spider silk is one technology with an immense product and market range and you’ve just amplified the potential many times over.  Thanks!


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