Montreal researcher builds world's smallest thermometer

Updated: Aug 2, 2018

Canada Research Chair Alexis Vallée-Bélisle published his results in the latest edition of Nano Letters

Marilla Steuter-Martin · CBC News · Posted: May 04, 2016 4:00 PM ET | Last Updated: May 5, 2016

Université de Montréal chemistry professor Alexis Vallée-Bélisle and his colleagues have successfully created ultrasensitive thermometers too small to be seen with the naked eye, using DNA nanotechnology. (submitted by Alexis Vallée-Bélisle) Université de Montréal chemistry professor Alexis Vallée-Bélisle and his colleagues have spent the last three years building a nanothermometer so small, they can't even see it.

Vallée-Bélisle, who holds the Canada Research Chair in bioengineering and bio-nanotechnology, says he only knows it's there because it's working the way it was designed to.

"The overall goal of the project was trying to build the smallest thermometer we could come up with. We know it's there because it's able to measure temperature exactly the way we want it to," he told CBC's Homerun.

The thermometer is composed of structures made from DNA molecules. These structures are design to auto-assemble since, at this scale, molecules are too small to be put together using nanotools.

20,000 times smaller than human hair

"The way an engineer builds is by crafting pieces together, but nano is too small for that. So now we have to find ways to do it otherwise. The thermometer measures five nanometres, so about 20,000 times smaller than human hair," said Vallée-Bélisle.

These structures are designed to assemble and unfold at various temperatures. By monitoring changes in the DNA structures using optical reporters, scientists can determine change in temperature on a nanoscale.

David Gareau, Arnaud Desrosiers and Alexis Vallee-Bélisle's findings in nanothermometry are published in the current edition of Nano Letters. (Nano Letters)

"We have enough knowledge of DNA chemistry so that we know how the structures form and behave. Temperature behaves differently at the nanoscale, and our nanothermometer will allow us to measure its effect precisely," said  Vallée-Bélisle.

The results of this three-year effort were published by Vallée-Bélisle and his colleagues at the university's Laboratory of Biosensors and Nanomachines, David Gareau and Arnaud Desrosiers, in the latest edition of Nano Letters.  Vallée-Bélisle says this technology could be used for a number of scientific applications.

"I am excited about figuring out how living nanotech works," he said. "In our cells, there are thousands of little machines, motors, moving parts. One question I'm asking right now is, 'Do these nanomotors generate heat as they work?' and, 'Has nature found a way to cool those machines?'"

He says this opens up a whole new field of study for nanoscale researchers.

"The human body is at 37 degrees, but inside living cells we don't know if there are different temperatures at the nanoscale. There probably are, but we have no tools to measure. This thermometer opens up the field into precisely measuring temperature at the nanoscale. I would say that's the big outcome of this study."

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