Chinese scientists working in collaboration with Louisiana State University have demonstrated a light bulb in with a carbon nanotube filament. As well as being the only real change in design in the last 125 years, the nano-filament bulb has several advantages over traditional tungsten.
Firstly, the researchers, lead by Tsinghua University's Jinquan Wei, found that the nano-filament emitted more light than tungsten at the same voltage. It also has a lower threshold for light emission: a mere three volts, as opposed to six for Tungsten. The bulbs still worked after being switched on and off 5000 times, and could operate at 25 volts for more than 360 hours.
The filament also behaves as a precise resistor over a wide temperature range: producing consistent resistance at up to 1750 Kelvin.
The experiment involved replacing the tungsten filament with a highly pure carbon nanotube version. The team made the tubes by chemical vapour deposition. After soaking in alcohol, the tubes self-organise into long filaments. The new filament was sealed, under vacuum, into an ordinary 40 watt bulb.
According to PhysicsWeb, the researchers say that although more work is needed, the bulbs could be commercially available in the next five years. ®