Australian engineers have come up with a way to use a diamond nanoparticle as a thermometer.

A team led by scientists from the University of Technology Sydney (UTS) has developed a highly-sensitive nano-thermometer that uses atom-like inclusions in diamond nanoparticles to accurately measure surrounding temperature.

The sensor exploits the properties of these atom-like diamond inclusions on the quantum level, where the limits of classical physics no longer apply.

Senior investigator Dr Carlo Bradac says the new technique is not just a “proof-of-concept realisation.”

“The method is immediately deployable. We are currently using it for measuring temperature variations both in biological samples and in high-power electronic circuits whose performance strongly rely on monitoring and controlling their temperature with sensitivities and at a scale hard to achieve with other methods,” Dr Bradac said.

Diamond imperfections are what give coloured diamonds their hue, and also allow them emit light at specific wavelengths when probed with a laser beam.

In some cases, the intensity of the light emitted by these diamond colour impurities depends very strongly on the temperature of the surrounding environment.

“We immediately realised we could harness this peculiar fluorescence-temperature dependence and use diamond nanoparticles as ultra-small temperature probes,” Dr Bradac said.

Because these diamond nanoparticles can be as small as just a few nanometres, they can be used as tiny nano-thermometers.

“This is particularly attractive as diamond is known to be non-toxic, thus suitable for measurements in delicate biological environments, as well as extremely resilient. This is ideal for measuring temperatures in very harsh environments up to several hundreds of degrees,” he added.

The researchers say that an important advantage of the technique is that it is all-optical. The measurement only requires placing a droplet of the nanoparticles-in-water solution in contact with the sample and then measuring - non-invasively - their optical fluorescence as a laser beam is shone on them.

More information is accessible here.