A medical imaging technique used by doctors to examine the health of human tissue, could now be used by engineers to examine the health of structures such as roads and bridges.
Electrical impedance tomography (EIT), which is widely used in the medical profession to monitor areas such as lungs where tissue is more resistant to normal x-rays, has now been applied to a carbon-nanotube-based sensor, for use by civil engineers. The findings have been published in the Journal of Nondestructive Evaluation.
The research was carried out by Erik Thostenson and Thomas Schumacher, both affiliated faculty members in the University of Delaware’s Center for Composite Materials.
Thostenson said: “While the feasibility of employing carbon-nanotube-based composites as sensors has been validated, the typical approach is to use a series of one-dimensional measurements collected from a two-dimensional sensing area. The problem is that this confines the possible damage locations to the grid points of the measurements. EIT, on the other hand, is a true 2D algorithm.”
Schumacher is a structural engineering researcher and he said that the technique can be scaled up, does not require a large amount of carbon nanotubes and is relatively inexpensive.
“Although we did encounter some issues with the size of cracks being overestimated and their shapes not being well represented, overall our EIT methodology was able to detect the initiation of damage well before it was visible with infrared thermography,” said Schumacher.
“We are in the process of making improvements to the EIT algorithm to increase its accuracy. After that, we plan to demonstrate it in the laboratory, with an aim toward scaling it up for future monitoring of real structures.”