Researchers from University at Buffalo in New York have developed a simple, inexpensive process for generating a polymer that emits many different wave-lengths of light. The findings from Buffalo’s engineering department appear online in the journal Advanced Materials (paid subscription required), for which a provisional U.S. patent application has been filed.
The engineers, led by electrical engineering professor Qiaoqiang Gan (pictured left) and Alexander Cartwright, the university’s vice-president for research and economic development, started with a compound of light-sensitive small-molecule chemicals called monomers, in the form of a thick liquid. They sandwiched the substance between two glass slides, and then sent a laser beam through a curved lens above the slides. When the beam hit the lens, it divided and bent into light of continuously varying wave-lengths.
When the various wave-lengths of light hit the chemical compound between the glass slides, the monomers in the substance began joining into longer molecular chains or polymers. The polymer structures formed into ridge-like patterns, with larger ridges taking shape where the light hit the substance with more intensity. The process resulted in a thin rainbow-colored filter, when viewed under white light, with periodic polymers — those arranged in a repeating sequence — in layers reflecting a continuous spectrum of colors.
While the published research produced a polymer filter only 25mm (about 1 inch) in length, Gan and Cartwright say the process is scalable, making it possible to vary the size of the filter by shining the light through lenses of different sizes. The single-step method for producing the filter is relatively simple and inexpensive, plus the colors are permanent, since they are produced from the filter’s surface geometry rather than pigments that can fade.
The ease of producing the polymer filter could lead to the development of small devices that connect with cell phones to conduct multi-spectral imaging for detecting disease. With this one application, and the process’s simplicity and low cost, says Gan, “we feel there is a huge market for improving clinical imaging in developing countries.”
The next steps for the researchers are to improve the quality of the rainbow filter, and explore ways to build the technology into handheld devices. Buffalo’s technology transfer office has submitted a provisional patent application detailing the production process to the U.S. Patent and Trademark Office.
* * *