Researchers at the Massachusetts Institute of Technology (MIT) in the US and the University of Potsdam in Germany are working on making a ‘sensing skin’ out of a TPE to detect cracks in concrete structures. The prototype skin is made of stretchy thermoplastic elastomer mixed with titanium dioxde. Patches of the skin are painted with black carbon to measure changes in the electrical charge of the skin. “The sensing skin has the remarkable advantage of being able to both sense a change in the general performance of the structure and also know the damage location at a pre-defined level of precision,” said researcher Simon Laflamme. “Such automation in the health-monitoring process could result in great cost savings and more sustainable infrastructures.” The skin is designed to be rolled out in patches across structures such as bridges and dams. The formation of a crack would cause a movement in the concrete in under the patch which would change the capacitance, or stored energy, of the skin. Once a day, a computer system attached to the sensing skin would send a current to measure the capacitance of each patch and detect any difference. Any flaws would therefore be flagged up every 24 hours. The proposed sensor is superior to conventional fibre-optic versions as two-dimensional readings can be collected from one sensor, said the researchers, adding: “The safety of civil infrastructures would be greatly improved by having detailed real-time information on structural health." The work was funded by the German Ministry of Education and Research.