Public release date: 21-Jun-2012 [ | E-mail | Share ]

Contact: David Ruth david@rice.edu 713-348-6327 Rice University

A new type of paint made with carbon nanotubes at Rice University can help detect strain in buildings, bridges and airplanes.

The Rice scientists call their mixture "strain paint" and are hopeful it can help detect deformations in structures like airplane wings. Their study, published online this month by the American Chemical Society journal Nano Letters details a composite coating they invented that could be read by a handheld infrared spectrometer.

This method could tell where a material is showing signs of deformation well before the effects become visible to the naked eye, and without touching the structure. The researchers said this provides a big advantage over conventional strain gauges, which must be physically connected to their read-out devices. In addition, the nanotube-based system could measure strain at any location and along any direction.

Rice chemistry professor Bruce Weisman led the discovery and interpretation of near-infrared fluorescence from semiconducting carbon nanotubes in 2002, and he has since developed and used novel optical instrumentation to explore nanotubes' physical and chemical properties.

Satish Nagarajaiah, a Rice professor of civil and environmental engineering and of mechanical engineering and materials science, and his collaborators led the 2004 development of strain sensing for structural integrity monitoring at the macro level using the electrical properties of carbon nanofilms dense networks/ensembles of nanotubes. Since then he has continued to investigate novel strain sensing methods using various nanomaterials.

But it was a stroke of luck that Weisman and Nagarajaiah attended the same NASA workshop in 2010. There, Weisman gave a talk on nanotube fluorescence. As a flight of fancy, he said, he included an illustration of a hypothetical system that would use lasers to reveal strains in the nano-coated wing of a space shuttle.

"I went up to him afterward and said, 'Bruce, do you know we can actually try to see if this works?'" recalled Nagarajaiah.

Nanotube fluorescence shows large, predictable wavelength shifts when the tubes are deformed by tension or compression. The paint -- and therefore each nanotube, about 50,000 times thinner than a human hair -- would suffer the same strain as the surface it's painted on and give a clear picture of what's happening underneath.

See the original post:

Nano-infused paint can detect strain