Futuristic microwave shield

Indian scientists develop novel material to block radiation

By Biplab Das
Published: Wednesday 15 August 2012

imageIT’S COMMON to see a laptop flicker if a cell phone starts buzzing nearby. The occurrence is known as electromagnetic interference (EMI) and happens due to the effect of microwave radiations from cellphones. In today’s technology dependent world there is no escaping these radiations.

They interfere with the functioning of other devices in the vicinity. There are concerns about the safety of these waves to human health. Researchers from the National Physical Laboratory (NPL) and the Indian Institute of Technology in New Delhi have now developed two materials to act as shields against the omnipresent microwaves. “The high value of these fabrics’ ability to attenuate microwave radiation supports their potential as futuristic microwave absorbers,” says lead researcher Parveen Saini of NPL.

Most materials designed to act as EMI shields are metal or carbon based and work by reflecting the waves. These materials, however, are heavy, costly, and difficult to produce in bulk. The new materials developed by the Indian researchers do not have such shortcomings. Made from everyday cotton fabric used in clothes, they absorb 97-99 per cent of microwaves.

The researchers mixed polyaniline with barium titanium trioxide or ferrous-ferric oxide nanoparticles. This mixture was then coated on the cotton fabric in presence of dodecylbenzenesulfonic acid (DBSA) to make the fabric. Published in the June 21, 2012 issue of the Journal of Physical Chemistry C, the study can help develop microwave absorbers of the future. The materials can be used as a microwave shield in various articles like mobile pouches, heart guards and as shielding curtains for hospital windows, says Saini.

Earlier studies had found that mixing nanoparticle-based shielding materials to cement can insulate rooms from interfering signals (see, ‘Do not disturb’, Down to Earth, December 16-31, 2011).

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