Name: Jerome Lynch
Affiliation: University of Michigan
Jerry Lynch is proud of his profession. He likes to point out, for instance, that the U.S. has more than 600,000 bridges, and that failures are extremely rare. “We have a very, very good track record,” he says. “We’re a diligent bunch, civil engineers.” But when something does fail, seriously bad things happen—like when the I-35W bridge collapsed in Minneapolis in 2007 and killed 13 people due to faulty gusset plates used to join load-bearing beams. It’s these catastrophic failures that motivate Lynch, an engineering professor at the University of Michigan, to think incessantly about how things come together and how to keep them from coming apart.
His solution to structural failures like the one that befell I-35W bridge is a “sensor skin” that continuously monitors weak spots and alerts inspectors to problems before they become dangerous. “Wouldn’t it be great if we could see big structural failures coming ahead of time?” he says.
Today, the few bridges in the U.S. that have any kind of sensors usually only track seismic activity, largely because it’s so expensive to wire a bridge with enough equipment to monitor multiple threats. “The Golden Gate Bridge is over a mile long,” Lynch says. “The special conduit needed can be $10 a foot, and one sensor can cost thousands.” So instead, engineers typically rely on visual inspections at two-year intervals.
Lynch’s sensors attach to wireless nodes that communicate with other nodes on the bridge, process the data on their own, and relay potential problems back to the local inspector’s office using a cellular data connection. Each sensor consists of polymer sheets up to a foot square and just a few microns thick that cover key structural elements, like the gusset plates that gave way in Minneapolis. At programmed intervals or on command from an inspector, a small microprocessor can send an electric current through the conductive carbon nanotubes embedded in the sheets, while electrodes gauge electrical resistance to detect strain, corrosion, load and dozens of other indications of stress. Hotspots are displayed on a computerized map of the bridge. Lynch doesn’t know yet how much each sensor will cost, but just the fact that they’re wireless will make them cheaper to deploy than today’s sensors and will eliminate the costs associated with unnecessary inspections.
Lynch knows about using time wisely. The Queens, New York, native earned a master’s degree and a Ph.D. in civil engineering from Stanford University and then went back and got another master’s, in electrical engineering. After 9/11, he launched a company to build wireless infrastructure sensors and left it to teach at Michigan, where he was named Professor of the Year his second year on the job. “Dr. Lynch is probably the most regarded scholar among his peers in such an early stage of a career,” says Kincho Law, a professor of structural engineering at Stanford.
Lynch’s sensing skin will leave the lab next year for testing on three highway bridges in Michigan and three bridges in Korea. And he is already working on a paint-based version that could be applied to anything that needs monitoring, from airplanes to pipelines, as well as a version that would make its own power from the vibrations of whatever it’s painted on. “There’s an inherent uncertainty in visual inspections,” Lynch says. “We need better tools to keep an eye on things.” —Mike Haneysingle page
Five amazing, clean technologies that will set us free, in this month's energy-focused issue. Also: how to build a better bomb detector, the robotic toys that are raising your children, a human catapult, the world's smallest arcade, and much more.