 Researchers at Rensselaer Polytechnic Institute have developed a simple new technique for identifying and repairing small, potentially dangerous cracks in high-performance aircraft wings and many other structures made from polymer composites. By infusing a polymer with electrically conductive carbon nanotubes and then monitoring the structure’s electrical resistance, the researchers were able to pinpoint the location and length of a stress-induced crack in a composite structure. When a crack is located, engineers can then send a short electrical charge to the area to heat up the carbon nanotubes and melt an embedded healing agent that will flow into and seal the crack with a 70% recovery in strength. Carbon nanotubes are seen randomly dispersed in an epoxy resin, which can be molded into different structures. Photo courtesy of Rensselaer/N. Koratkar