"You can basically think of it as a litmus paper for carbon dioxide," said Al Meldrum, professor in the Department of Physics and co-author on the study led by graduate student Hui Wang. "The work showed that you can make a sensitive carbon dioxide detector out of a simple piece of paper. One could easily imagine mass produced sensors for carbon dioxide or other gases using the same basic methods."

The sensor, which changes colours based on the amount of carbon dioxide in the environment, has many potential applications -- from industries that make use of carbon dioxide to smart buildings. And due to its paper base, the sensor is low cost to create and provides a simple template for mass production.

"In smart buildings, carbon dioxide sensors can tell you about the occupancy and where people tend to congregate and spend their time, by detecting the carbon dioxide exhaled when we breathe," explained Meldrum. "This can help to aid in building usage and design. Carbon dioxide sensors currently can be very expensive if they are sensitive enough for many applications, so a cheap and mass-produced alternative could be beneficial for these applications."

While this research demonstrates the sensing ability and performance of the technology, a mass-producible sensor would require further design, optimization, and packaging.

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Journal Reference:

1. Hui Wang, Sergei I. Vagin, Bernhard Rieger, Alkiviathes Meldrum. An Ultrasensitive Fluorescent Paper-Based CO2 Sensor. ACS Applied Materials & Interfaces, 2020; 12 (18): 20507 DOI: 10.1021/acsami.0c03405