Q&A | U of A researcher on battery-free sensor to track vital signs in extreme cold

University of Alberta and Canada’s Department of National Defence researchers have developed a tiny battery-free sensor that can be used to track vital signs and detect frostbite in soldiers in extreme cold. But its potential uses don’t stop there.

Ashwin Iyer, a professor at the University of Alberta’s engineering faculty, leads the team working on a multi-year project with the Department of National Defence’s Innovation for Defence Excellence and Security program.

Iyer said the idea behind the program is to use commercial telecommunications technology for the military. He said the university has world-leading research on technology that is low in size, weight, power and cost, also known as SWaP-C systems.

Iyer spoke with CBC’s Shannon Scott on The Trailbreaker on Wednesday.

This interview has been edited for length and clarity.

What problem were you trying to solve when you started working on this?

We envisioned the following scenario: Canadian or allied soldiers on a battlefield in extremely harsh conditions. For example in the High Arctic, commanders off the field need to track the health of their troops in order to identify potential health issues, such as frostbite, to get them the help that they need. We envisioned a network of soldier-worn biometric sensors to track vital signs such as heart rate, respiration, core body temperature and temperature at the extremities. The idea was to do what we can, short of picking up rifles, to support our soldiers in these situations that they faced in protecting our freedoms.

These sensors have been designed to work in temperatures as cold as -70 C. Why do traditional battery-powered devices fail in that kind of environment?

We’ve all experienced a situation where we pull out our phones when it’s extremely cold and they suddenly shut down. That’s because lithium ion battery technology does not do well in the cold. It’s something that research groups and companies all over the world are trying to address. We wanted to eliminate the batteries entirely. So [we found a way] for these sensors to harvest energy from their environments.

How do these sensors maintain power?

There are different ways to do it. For example, you could harvest energy just from motion, from walking. The technology we’re using in these sensors is based on radio frequency identification technology, which we encounter in everyday life all the time.

The way we track them [uses] the same type of waves that we use to communicate with our cell phones. There are tiny chips that absorb the energy from this radio frequency wave to power themselves up, then they use that to do the sensing and return a signal [with the information] like a mirror. 

How did you come up with that?

We had to have these systems meet several criteria: the sensors have to be wireless, they have to be ultra small so that they wouldn’t interfere with regular operations. The antennas that make these sensors wireless are often the largest parts of these wireless systems and miniaturizing them means they stop working like antennas, we had to reach into about 80 years of antenna research down to the fundamental physics to find a way to miniaturize them. 

One of the goals was to detect frostbite before it becomes serious. What would that look like in real time for someone in the field wearing gloves with this technology?

[We would have] one [sensor] detecting core body temperature and another on the fingertips, where the frostbite will take place first. We have these readers that are analyzing the temperature at these various points and when it gets to a certain threshold, it raises a flag.

The idea is to sound an alarm to provide sufficient time to bring some help to that person.

I’m wondering beyond military use, how you see this technology potentially being used in the north?

Military is just one use case, the direct counterpart would be emergency response. We want to be able to track the health status of anybody who puts themselves in harm’s way.

These sensors go down to -70 C but they also go up to very high temperatures. So they can be used across the globe.

But they have other uses.

The interesting thing about these sensors is they can detect all very different parameters. [They could be used] just to detect something in your home, for example, flooding in a basement or carbon monoxide. There are multiple uses, often the technologies that we rely on every day in some way or form started with investment in military innovation, this may be one of those situations.