Joined: 16 Mar 2004
|Posted: Wed Sep 20, 2006 10:16 am Post subject: Carbon nanotube nanothermometers
|Carbon nanotube nanothermometers
by Michael Berger
The oxidation-assisted temperature measurement with carbon nanotube nanothermometers that contain liquid gallium is a novel and reliable method that can be used over a moderate temperature range and can be applied in any environment where air is present.
All the other available techniques that are capable to measure temperature at the nanometer scale are limited by either that they are only workable in a very narrow temperature range or that they can only be applied in a special environment.
One particular problem to arise from both the continuing miniaturization of existing technologies and the advent of nanotechnologies is that conventional devices for temperature measurements, such as thermometers and thermocouples, are not capable of measuring the temperatures of these systems at the scale on which they operate. Thus, a pressing scientific problem is the need for a viable technique for measuring temperature at the nanoscale.
A previous approach in using carbon nanothermometers focused on a single nanothermometer and involved preliminary calibration in a transmission electron microscope (TEM) to record the initial level of the liquid Ga. The complexity of this approach is that the same nanothermometer needs to be found again after use to make the final reading in a TEM.
In a novel approach, researchers at the NANO Major National Research Facility based in the Australian Key Centre for Microscopy and Microanalysis at the University of Sydney, and the Advanced Materials Laboratory at the National Institute for Materials Science in Japan, came up with a one-step procedure without the need for any calibration process. It provides a simpler and, importantly, a far more reliable way to measure temperatures over a moderate temperature range at the nanometer scale.
When a Ga-filled carbon nanotube is heated in air for an appropriate length of time, an oxide marker is formed on the inner wall of the carbon nanotube due to partial oxidation of the Ga. Thus, the temperature to which the nanotube was exposed can be retrieved by progressively heating the carbon nanotube until the liquid Ga reaches the oxide marker.
This story was first posted on 20th July 2006.