New retroreflective material could be used in nighttime color-changing road signs

0
9

A thin film that reflects light in intriguing ways could be used to make road signs that shine brightly and change color at night, according to a study published in Science Advances.

The technology could help call attention to important traffic information when it’s dark, with potential benefits for both drivers and pedestrians, researchers say.

The film consists of polymer microspheres laid down on the sticky side of a transparent tape. The material’s physical structure leads to an interesting phenomenon: When white light shines on the film at night, some observers will see a single, stable color reflected back, while others will see changing colors. It all depends on the angle of observation and whether the light source is moving.

An image series shows how a new retroreflective material can be used to make a color-changing speed limit sign. Boxes A-F show how the sign changes color, from the perspective of drivers on the road, as they pass by. Image credit: Fan et al., Sci. Adv. 2019; 5 : eaaw8755. This work is licensed under CC BY-NC

The research was led by Limin Wu, PhD, at Fudan University in China, whose group developed the material. Experts on optics at the University at Buffalo made significant contributions to the work, providing insight into potential applications for the film, such as employing it in nighttime road signs.

“You can use this material to make smart traffic signs,” says Qiaoqiang Gan, PhD, an associate professor of electrical engineering in the UB School of Engineering and Applied Sciences and a co-first author of the new study. “If a person is listening to loud music or isn’t paying attention while they’re walking or driving, a color-changing sign can help to better alert them to the traffic situation.”