A new, extended-range optical sensor developed by ECE’s Center for Photonics Technology (CPT) may boost the country’s ability to monitor pipelines, power and communications lines, bridges, dams, and other structures. Real-time infrastructure monitoring is important for homeland security and for protecting communities from natural hazards, such as earthquakes and hurricanes.
A research team led by Anbo Wang, director of CPT has received a $500,000 grant from the National Science Foundation to investigate the use of a UV-induced intrinsic Fabry-Perot interferometric (IFPI) fiber sensor for infrastructure monitoring. The technology will be tested with a wide area network spanning 250 miles between northern Virginia and Blacksburg.
Infrastructure monitoring requires networks with millions of sensors that measure temperature, strain, pressure, chemical, biological, and acoustic properties, and transmit the data over long distances. Full-scale monitoring networks would include sensors of different types and the ability to withstand interference and harsh environments. Due to the quantity of sensing points required, low cost and low maintenance are critical issues.
Most technologies considered for monitoring involve low-cost, batch-produced, semiconductor electronic sensors, such as MEMS, according to Wang. With wireless transmission, many sensors can be deployed over a large area. “Such sensors, however, are susceptible to electromagnetic interference (EMI), have rather limited capability of multiplexing, and are typically limited to operating under 125° C,” he said. “This is a drawback for defense and homeland security monitoring.”
Optical sensors are insensitive to EMI and enjoy greater temperature ranges, but the current optical sensor technologies are more expensive and present limited multiplexing capability — only several hundred sensors along a single fiber cable, Wang estimated.
Last year, Wang’s group developed new methods for fabricating and spacing sensors within optic fibers, using a focused ultraviolet (UV) laser beam and metallic masks. The sensors, UV-induced IFPIs, have demonstrated greater range and denser multiplexing capability.
“With this technology, we believe we can increase the multiplexing capability of optical sensor networks by at least an order of magnitude,” he said. His team, which includes CPT associate director Gary Pickrell and ECE research scientist Kristie Cooper is working with ECE’s Luiz DaSilva, a large-scale network expert, and mathematician, Tao Lin, to develop the optical networking technology, models, and data fusion and decision-making techniques for a large-scale system.
The team plans to deploy three 1000-sensor clusters over a wide area network spanning the distance between the Blacksburg campus and the Alexandria Research Institute. “With our sensor design and computer networking, we can obtain a revolutionary increase in sensor multiplexing density for large area coverage of measurements with high spatial resolution and harsh environment capability. Such capabilities will enable real-time monitoring of critical infrastructure at a scale previously unrealizable,” Wang said.