Kirill Larin, assistant professor of biomedical and mechanical engineering at the University of Houston, has received a $400,000 grant from the US Navy to develop a laser-based system that can diagnose decompression sickness -- sudden, drastic changes in the air or water pressure surrounding a body -- in a matter of seconds. Larin's device will be the first optical, noninvasive tool to test those likely to suffer from the sickness, such as scuba divers, submariners, airplane pilots and astronauts at the International Space Station. Decompression sickness causes the joint pain known as "the bends," and can lead to seizures, stroke, coma and death. It often isn't treated until symptoms appear. Larin’s optical device can locate the presence of nitrogen gas, or microbubbles, in blood and tissues, which can restrict the flow of blood throughout the body and cause damage. He is developing the tool, which works much like an ultrasound machine, with Dr. Bruce Butler of the University of Texas Health Science Center in Houston. Instead of using sound waves, Larin’s system uses light waves in the form of lasers that bounce back when they encounter resistance, providing a high-resolution image. The presence of microbubbles in the blood or tissue could be quickly determined by shining the laser on Navy divers or pilots returning to the surface, and treatment started before symptoms appear. An early version of the tool has located microbubbles as small as 6 µm, or six thousandths of a millimeter. Most microbubbles are between 5 and 15 µm, about the size of a red blood cell.