Joined: 16 Mar 2004
|Posted: Fri Aug 15, 2008 8:38 am Post subject: New look for nanothermometers
|12 September 2007 NanoTechWeb
New look for nanothermometers
by Belle Dumé
A new electromechanical nanothermometer has been designed by scientists in the UK and Russia. The device would work by measuring the change in conductivity of a double-walled carbon nanotube when it is in contact or filled with a sample. It could be ideal for applications in the semiconductor industry to monitor the temperature of single chips and in nanobiology.
Yurii Lozovik of the Institute of Spectroscopy in Moscow and Elena Bichoutskaia from University Chemical Laboratory in Cambridge and colleagues have put forward a method to determine temperature on the nanoscale by measuring the conductivity of a carbon nanotube. The method works on the premise that the conductivity of the system changes thanks to thermal vibrations on the nanotube walls created by the presence of the sample. These vibrations alter the relative position of the walls on the sub-nanometre scale.
In 2002, a research group in Japan made a different type of nanothermometer in which temperature was measured by monitoring the thermal expansion of a column of liquid gallium inside a carbon nanotube 10 µm long. This thermometer, which is similar to an ordinary clinical thermometer albeit billions of times smaller, must be calibrated and read in a transmission electron microscope, which greatly limits its use in nanodevices. The new thermometer does not have this major drawback and could be calibrated using a thermocouple, explains Lozovik.
The team, which also includes scientists from Volograd State University, says the device could be used in a number of applications. "Sets of these nanothermometers could be inserted into a chip for permanent monitoring of temperature distribution inside the chip at nanoscales," Lozovik said . He added that the thermometer could also be used to measure the temperature of a single cell – for example to identify a cancer cell that has a higher temperature than a healthy one.
The researchers are now working on identifying the operating characteristics of their device. "A new paper concerning applications of these nanothermometers in medical robots has been accepted for publication in the International Journal of Nanomedicine,” said Lozovik.