What you are looking at here is an extremely small radio. It is a single carbon nanotube which is one ten-thousandth smaller in diameter then a human hair. It is powered by a battery and earphones can be connected. Obviously you are not going to have a radio you cannot even see, so what's the practical use? It could be used for putting inside your body to monitor via radio control. Also it could be used to work inside a mobile phone.
Video found here Via: Technonix