The minuscule size of most nanotubes – hollow cylinders of carbon
measuring only a few billionths of a meter wide – boggles the mind. Even more astounding may be that scientists can conceivably nestle these straws inside one another like Matryoshka dolls, with the inner set of tubes sliding in and out a billion times a second. Such gigahertz oscillators could aid in the creation of nanomechanical devices.
Scientists continue to create new uses for carbon nanotubes, those tiny cylinders comprised of pure carbon. A paper published today in the journal Nature describes a thermometer made out of a column of carbon just 10 micrometers long. According to the report, the nanodevice can measure temperatures between 50 and 500 degrees Celsius and “should be suitable for use in a wide variety of microenvironments.”
Yihua Gao and Yoshio Bando of the National Institute for Materials Science in Ibaraki, Japan, filled nanotubes less than 150 nanometers in diameter with a one-dimensional column of liquid gallium. In larger quantities, liquid gallium has one of the widest temperature ranges of any metal, spanning 30 to 2,403 degrees C. The researchers determined that nanoquantities of the metal behave similarly and that the liquid’s behavior within the tube changes predictably with temperature.
Like the mercury in a conventional thermometer, the minuscule meniscus in the nanodevice moves up and down as the gallium expands and contracts in response to temperature. Gao and Bando suggest the new nanothermometer will extend temperature measurements in very small systems beyond the four to 80 kelvins range that current electronic-based devices can achieve.