Sensors that measure the strain or forces exerted on materials in everything from airplanes to civil infrastructure have one vital flaw; they can break under stress rendering themselves useless but not necessarily the material they were monitoring. Researchers from North Carolina State University have overcome this by designing a sensor that can measure strain in structural materials and is capable of healing itself, allowing for continued collection of data that can help determine structural safety in the wake of earthquakes, explosions, or other unexpected events.
The sensor contains two glass optical fibers that run through a reservoir filled with a ultraviolet (UV)-curable resin. The ends of the glass fibers are aligned with each other, but separated by a small gap. Focused beams of infrared and UV light run through one of the fibers, and when the UV beam hits the resin, the plastic hardens, creating a polymer filament that re-connects the glass fibers and creates a closed circuit for the IR light. The rest of the resin in the reservoir remains in liquid form, surrounding the filament....