How many times we wished to limit our wi-fi signals inside the four walls?What if a  special paint on walls stop those signals passing through it ?

“Anti wi-fi paint” does the same. It is a special paint that doesn’t allow wireless to pass through. The secret is mixing aluminum-iron oxide particles  with the paint. The metal particles resonate at the same frequency as Wi-Fi and other radio waves, so signals can’t pass through the thin layer of pigment. Outsiders would simply be unable to access your wireless network, just as you, inside the house, won’t be able to interlope on anything beamed on the outside.

Developed by the University of Tokyo, the paint is said to be the first that can block radio frequency in higher spectra where Wi-Fi and other higher-bandwidth communications occur rather than just low-frequency wireless like FM radio. Most Wi-Fi technologies operate at 2.4GHz; the Tokyo paint can reportedly block frequencies all the way up to 100GHz, with a 200GHz-blocking paint now in the works.

The paint has a number of interesting potential applications including: keeping wireless networks secure, blocking phone calls during movies, shielding hospital rooms from unwanted electromagnetic radiation, and making clothes that protect people from electromagnetic waves.

Source: http://tech.yahoo.com