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optics. Los Alamos researcher Judith Mourant is a light scattering expert using fiber optics to pioneer a new method to detect cervical cancer. Cervical cancer is still a common cancer for American women, despite an enormous decrease in incidence since the implementation individual white pixels doubling up on output of regular screening in the 1950s. After initial Organic Light by combining fluorescence with phosphores- screening via the Papanicolaou test (a.k.a. Pap cence. smear), abnormal or suspect findings are sub- About 15 percent of the average American “Phosphorescence normally won’t happen,” jected to more sensitive diagnostic procedures, household’s electricity goes to lighting—and Tretiak says, “unless you provide certain metals primarily colposcopy (illuminated magnifica- existing lighting technologies are notoriously that enable crossings between fluorescing and tion) and biopsy (tissue sampling). Biopsies inefficient. Even today’s green-tech compact phosphorescing states.” He and his collaborators are small portions of tissue and their removal fluorescent bulbs and LED lamps convert only selected atoms of platinum and inserted them (typically by scalpel or laser) can cause pain, 8–14 percent of the electricity they consume at particular intervals along the chainlike OLED infection, or other complications. Combine this into light. Nonetheless, that’s still many times with the stress of waiting for results, and some better than incandescent bulbs, which are only polymer molecules. When inserted at every chain link, the polymer produced violet fluo- patients wind up avoiding the procedure until it 2–3 percent efficient. According to the U.S. Department of Energy, rapid adoption of exist- rescence and yellow phosphorescence; at every may be too late. Furthermore, biopsies can only third chain link, it produced blue fluorescence sample a small portion of the tissue. To improve ing LED lighting over the next 20 years could and orange phosphorescence. Both mixtures this, Mourant and her team developed a nonin- save the country $265 billion and eliminate appeared whitish, and the team demonstrated vasive fiber-optic method that can improve the the need for 40 new power plants. Better yet, that truly white light should be possible after process of choosing when and where to biopsy in theory, future LED lamps could operate at a little tinkering with more complex platinum that could eventually decrease both the cost of a staggering 40-percent efficiency or slightly spacing, to adjust the colors and their relative detection and stress to patients. more, blowing away everything that exists intensities. Mourant, along with former Los Alamos cell today. Does that mean the OLED-lighting revolu- biologist James Freyer, previously showed that Los Alamos materials scientist Sergei Tretiak, tion is already upon us? “Not just yet,” admits cancerous cells scatter light differently than working with colleagues at the University of Tretiak. The team’s experiments used an noncancerous cells. When you hold a flashlight Utah and Nanjing University in China, recently against your palm in a dark room, your hand made important headway toward that tantaliz- additional light source to deliver energy to the polymers, but a true OLED would supply will glow red. The red color is because your tis- ing 40 percent. The team experiments with the energy with electricity instead. “So there’s sue absorbs the other colors of light, especially organic LEDs, or OLEDs, made from organic- polymer semiconductors instead of traditional another step to go,” says Tretiak. “But producing blue and green, while the red light, reflected off your blood cells, passes through. But it doesn’t semiconductors like silicon. They have a flexible, multiple colors from a single polymer gets us much closer.” go straight through the tissue of your hand—it plastic appearance and are currently used in is scattered, or bounced around, by microscopic computer, smartphone, and high-end television structures it encounters along the way. When displays. In these applications, red, green, and —Craig Tyler light bounces off of structures in tissue, the blue fluorescing OLEDs combine to make each change in intensity of the scattered light can be pixel. The same can be done to make white Brighter Future for Cancer Detection quantified and used to infer information about light for OLED lamps (as is currently done for the physical properties and structure of the LED lamps), but this approach is prohibitively What do high-speed communication, tissue. expensive. Instead, the objective for OLED advanced microscopy, high-tech security After proving her method in laboratory- lighting, if it is to reach that approximately systems, and noninvasive cancer detection have 40-percent theoretical limit, would entail in common? They are all made possible by fiber cultured cells, Mourant and her colleagues A flexible OLED device (left) and prototype OLED lighting panels CREDIT: meharris (left) and STRONGIk7/Wikime- dia Commons 1663 April 2014 27