Researchers at Princeton have developed a rubberized material that can be places over the surface of objects and detect cracks in the surface. How? An organic laser is deposited on the surface of the sheet of rubber. When the rubber stretches, the color of light emitted changes, allowing structural engineers to more readily observe any changes in the structure. Researchers have been focused on using sensor arrays for such applications; however, a stretchable laser would cover more area than wires or fiber optics. The device is made from a specially prepared sheet of polydimethylsiloxane (PDMS) that is made to have a wavy surface and which is covered with organic molecules. The lasing effect occurs when the material is exposed to an ultraviolet laser. Once photons are emitted, the material’s surface acts like a diffraction grater, amplifying the signal. The stretchable sensor was constructed by Sigurd Wagner, professor of electrical engineering at Princeton, with Patrick Gorrn, a researcher at Princeton. Wagner says that his prototype still needs to be fine-tuned. While the PDMS sheets can stretch a great distance, the organic layers sheer off when they're extended too far. Fixing this problem will likely come down to testing different types of light-emitting molecules and finding a way to better affix them to the PDMS. “We know the experiments to do,” he says. “We just haven't found the magic recipe yet.” If only this material covered all space-shuttles and rockets, many catastrophes could have been avoided.

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