University of Rhode Island researchers developed an advanced optical strain gage they claim is 100 times more sensitive than electrical strain gages. "Our gage is entirely temperature independent," says Otto Gregory, associate dean and professor of chemical engineering. "Electrical gages are annoyingly sensitive to temperature, so they need all sorts of additional circuitry and software to compensate for it. Ours doesn't, so it's cheaper to use," he adds.

The gage uses glass optical fibers with an inner diameter of just 500 mm embedded in or attached to a structure. Laser light is pumped into one end. Strain on the structure bends the tube and changes the light intensity detected at the opposite end. The tubes are layered with thin films of semiconductors or polymers having different light refraction indices.

The gage could see use in aerospace applications such as airplane wings, landing gear, and other equipment prone to flexing and fatigue.