Fiber light source shows promise for photodynamic therapy

Researchers from the Massachusetts Institute of Technology (MIT; Cambridge, MA) Research Laboratory of Electronics (RLE) have developed a fiber light source with varied brightness that could enable medical devices to be threaded into narrow openings to irradiate diseased tissue while leaving healthy tissue untouched. The fiber could prove useful in photodynamic therapy (PDT), a method in which light activates injected therapeutic compounds only at targeted locations.

The newly developed fiber—which measures 400 µm across—has a hollow core surrounded by alternating layers of materials with different optical properties, which together act as a mirror. In the core is a droplet of fluid that can be moved up and down the fiber. Then, a laser pumps the droplet to make it emit light—which bounces back and forth between the mirrors, emerging from the core as a 360° laser beam. Surrounding the core are four channels filled with liquid crystals, which vary the brightness of the emitted light; each liquid-crystal channel is controlled by two electrode channels running parallel to it.

A new fiber developed at MIT emits blue laser light only at a precisely controlled location. (Image courtesy of Greg Hren)

The paper is the work of seven researchers affiliated with the RLE, including Yoel Fink, a professor of materials science and electrical engineering and the RLE’s director; John Joannopoulos, the Francis Wright Davis Professor of Physics; lead author Alexander Stolyarov, a graduate student at Harvard University who is doing is Ph.D. research with Fink’s group; and Lei Wei, a postdoc at RLE. The work was funded by the U.S. Army and the National Science Foundation, through MIT’s Institute for Soldier Nanotechnologies and Center for Materials Science and Engineering.

For more information on the work, which appears in Nature Photonics, please visit http://www.nature.com/nphoton/journal/vaop/ncurrent/full/nphoton.2012.24.html.

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