he world’s smallest thermometer consisting of a single carbon nanotube filled with liquid gallium has been created by researchers in Japan. The instrument is so sensitive that it can measure the temperature change that occur when small groups of molecules react with each other.The nanothermometer is 10 micrometers long and has a diameter of only 75 nanometers. It length is about one tenth the width of a human hair.

“It’s interesting that nanotubes are being used in this way,” says Cees Dekker, a researcher at Delft University in the Netherlands. “Maybe they can be used as normal tubes after all.”

But the nanoscopic thermometer also has practical applications. It can reliably measure a broad range of temperatures when viewed using a high-powered electron microscope, say the researchers who created it.