Nanomaterials used in the sensors have a strong affinity to CO2, forming a molecule that interacts with a simple pH indicator. Different colors on the pH indicator reflect different CO2 concentrations. (Image: Roya Maboudian)
Q. What accounts for their small size and sensitivity?
A. Sensitivity is directly related to the surface area and the chemical affinity of the material for CO2. Our sensor is based on a porous material that has high surface area and strong affinity to CO2. As the CO2 interacts with this material, it forms an intermediate molecule. This molecule reacts with a third molecule, called a pH indicator, which changes color depending on the CO2 concentration. The sensor operates without any electrical power. High surface area also means we need very little material, so the sensor can be very small and lightweight.
Q. How sensitive are they compared to the expensive NDIR sensors?
A. They are currently not as sensitive or quantifiable as the NDIR technology. We need to more precisely link color change to CO2 levels. Our objective is not to compete with NDIR sensitivity, but to provide a more qualitative measure of CO2 for situations where size, power and price are critical, as in monitoring for individuals.
Q. They are simpler and smaller than the NDIS sensors. It seems they would not cost as much to produce and use.
A. That's right. They are made of inexpensive nanomaterials that can be placed on a cheap substrate such as a filter paper. So, we expect that they would be very economical.
Q. What do you think is the market for small, individual CO2 sensors?
A. There is a growing interest in people wanting to know what they are exposed to, both at work and at home. Parents are concerned about their children’s exposure. Employers wants to insure a healthy and productive workplace for their employees. It’s impractical to carry a large number of NDIR sensors, each the size of a small book.
Q. What work needs to be done before they are ready for commercialization?
A. Of course, the sensors are not as simple as they sound. Adrian Davey, our Bakar Innovation Fellow, is measuring the sensitivity to CO2 concentrations typical of indoor air and quantifying the color response.
We are also concerned with the stability of our porous material. How long will the material function? What is its shelf life?
These are critical to demonstrate the sensors’ commercial potential.
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