Question and Answer A researcher’s experiment on battery-free sensors to track vital signs in extreme cold

Researchers at the University of Alberta and Canada’s Department of National Defense 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.

Professor Ashwin Iyer, of the University of Alberta’s Faculty of Engineering, leads the team working on a multi-year project with the Department of National Defense Innovation for Defense 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 imagined the following scenario: Canadian or Allied soldiers on a battlefield in extremely harsh conditions. In the High Arctic, for example, commanders out in the field need to monitor the health of their troops to identify potential health problems, such as frostbite, so they can get the help they need. We envisioned a network of biometric sensors worn by soldiers to track vital signs such as heart rate, respiration, core body temperature, and temperature at the extremities. The idea was to do whatever we could, besides picking up a rifle, to support our troops in the circumstances they faced in defending our freedom.

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

We all have experienced the situation where we take our phones out when it is extremely cold and they suddenly turn off. This is because lithium ion battery technology does not perform well in the cold. This is something that research groups and companies around the world are trying to address. We wanted to eliminate batteries completely. So (we found a way) so that these sensors can receive energy from their environment.

How do these sensors maintain power?

There are different ways to do this. For example, you can get energy only from movement, from walking. The technology we are using in these sensors is based on radio frequency detection technology, which we encounter all the time in everyday life.

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

How do you think about it?

We had to make these systems meet several criteria: the sensors must be wireless, they must be very small so that they do not interfere with regular operations. The antennas that make these sensors wireless are often the largest part of these wireless systems and making them smaller means they stop acting like antennas, we had to access nearly 80 years of antenna research down to fundamental physics to find a way to make them smaller.

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

(We have) one (sensor) to detect core body temperature and another on the fingers, where frostbite will occur first. We have these readers that are analyzing the temperature at these different points and when it reaches a certain threshold, it raises a flag.

The idea is to sound the alarm to provide enough time to get some help to that person.

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

Military is only one use case, its direct equivalent would be emergency response. We want to be able to keep track of the health status of anyone who is self-harming.

These sensors go down to -70 C but they also go up to much higher temperatures. Therefore they can be used all over the world.

But they have other uses too.

The interesting thing about these sensors is that they can detect all different parameters. (These can be used) only to detect something in your home, for example, basement flooding or carbon monoxide. It has many uses, often technologies we rely on every day in some form or another, started with investment in military innovation, this could be one of those situations.