Researchers at the University of Montreal have created a thermometer that's an astonishing 20,000 times smaller than a single human hair. The work could lead to significant improvements in our understanding of how the human body functions on the nanoscale.

We've known for decades that DNA molecules change when they're heated up, and recent discoveries have shown us that molecules such as RNA and proteins are used to report temperature changes in the body. But might it be possible to create nanoscale thermometers to use for our own means?

Well, thanks to a new study, we now know that the answer is yes. According to the researchers, one big benefit of working with DNA is that, in relative terms at least, it's fairly simple. It's made up of four different molecules called nucleotides, the interactions between which are predictable, making them easily programmable.

Based on those known interactions, the team was able to create structures that fold or unfold at specific temperatures. By adding an optical element, they were then able to easily detect signals produced when a certain temperature was hit, all with a thermometer than measures just 5 nm in width.

Aside from being an extremely impressive achievement in their own right, the tiny thermometers may have a big impact on our understanding of molecular biology.

"There are still many unanswered questions in biology," said senior author Professor Vallée-Bélisle. "For example, we know that the temperature inside the human body is maintained at 37° C, but we have no idea whether there is a large temperature variation at the nanoscale inside each individual cell."

Full details on the research are published online in the journal Nano Letters.