This Gold Nanoparticle Paint Changes Color Based on Touch

A team of chemists at the University of California, Riverside, recently had a happy accident. While experimenting with stringing gold nanoparticles together, they noticed that the gold kept changing colors from a bright blue to purple to red. Indeed, the more they touched it, the more the color changed.

After a little bit of tinkering, the scientists successfully manipulated these self-assembled gold nanoparticles into a polymer film that can be applied like paint. Touching the film would cause the gold nanoparticle strings to stretch, and the color of the polymer to change.

"We have developed a high-resolution pressure sensor that indicates pressure by varying its color—a sensor that all of us can use with just our eyes," explains Yadong Yin who led the research. "When linked together, the gold nanoparticles originally appear blue. But they gradually change to red with increasing pressure as the nanoparticles start disassembling." This works differently from existing pressure-sensitive paints, used to measure aerodynamics.

As The Atlantic's Adrienne LaFrance put it, "It's like Hypercolor but for touch instead of heat." The implications reach far beyond fashion, though. Yin's team says the new technology could prove useful in crash test dummies, so that safety experts could see where impacts happen. Since the gold nanoparticles respond to different types of pressure, this would allow them to gauge the severity of blows. It could also inform other recent studies showing how interconnected gold nanoparticles respond to changes in the environment.

But really, you know you want a T-shirt made out of this stuff. Imagine if someone patted you on the back and the handprint stuck around for a week? It'd be a lot more fun than that broken old Hypercolor you're still trying to wear. [The Atlantic, UC-Riverside]

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