Do not disturb

REMEMBER the last time when your phone rang and the image in the nearby TV started shaking? Such a disturbance, which can also affect an airplane’s equipment when mid-air, is called electromagnetic interference. These disturbances can occur anywhere in the electromagnetic spectrum; the most common range of concern is 10⁴ Hz to 10⁸Hz.

Such interfering signals can be reduced by using materials that have a shielding effect. Researchers led by Avinash Pratap Singh and S K Dhawan at the National Physical Laboratory and the Department of Physics and Astrophysics, University of Delhi, have prepared a composition from graphene oxide nanosheets and a fluid containing ferric oxide nanoparticles. This composition can be added to cement to build rooms that do not allow interfering signals. When exposed to electromagnetic radiation, the composition could shield the transmittance by 99 per cent, say the researchers.

Graphene oxide imparts hardness to cement, while the fluid helps increase the effect of shielding. The composition relies more on absorption than reflection of electromagnetic radiation. “The idea is to design structures so that electromagnetic signals do not interfere with high tech equipment,” says Dhawan. It could also be used to coat enclosure in which electronic devices are kept, say the researchers in the October issue of Nanotechnology.