Academic researchers have developed physical color technology, which could potentially and dramatically change image printing by making it unnecessary to coat material with ink or chemicals. Precisely inscribed grooves are used to generate an observable color in the lab of University of Michigan Professor Jay Guo. “Rather than using these chemicals, you could basically emboss the structure — a very ‘green’ print technology,” he said. The structural color process would not only make printed products greener but also less susceptible to fading.
“[Current print companies are] using huge amounts of chemicals,” Guo said. “A press company is not exactly the greenest place. In the future, this can all be done using structural color and it would be long lasting.” The process employs nanocavities that trap light at specific wavelengths reliant on the cavities’ depths. The cavities’ structure lets them display color to an observer. “It’s purely a physical effect,” Guo said. The researchers can produce many different hues by varying the depth of the cavities. Guo calls this a selective property, as each depth corresponds to a distinct observable color.
The cavities are fabricated through a very precise nano-imprint method. “We cannot even see these [nanocavities] with an ordinary microscope because [the size] is beyond the diffraction limit,” Guo said. The technology also has possible uses in anti-counterfeiting efforts because of a property that complicates replication. “You can only see this kind of structure when the electrical field is perpendicular to the grating,” Guo said.