Researchers Improve IAQ With Upgrades to Sensors That Detect Formaldehyde

Common household items like cleaning products, candles, cribs, and makeup emit formaldehyde—a colorless, odorless chemical that has been found to be a risk to human health. But new, low-cost technology designed by researchers at Carnegie Mellon University (CMU) could lower these risks by making indoor air quality (IAQ) sensors last longer and catch unsafe formaldehyde levels sooner.

Air quality sensors typically use MXene, a class of compounds that is good at storing energy and sensing gases. But the compound is highly susceptible to oxidation, particularly when exposed to air and/or humidity, which poses a major challenge for MXene-based air quality monitors.

Researchers were able to lengthen the lifespan of the air quality sensor by using a unique polymer coating that extends the sensor’s half-life by more than 200% and enables it to regenerate when its performance begins to degrade.

CMU researchers, led by Professor of Mechanical Engineering Reeja Jayan, used a technique that vaporizes specific materials, causing them to form a nano-coating on the cold sensor in a way similar to condensation coating the outside of an ice-cold drinking glass on a hot day.

Without the coating, the MXene sensor lasted for a little over two months. But when the polymer layer was applied, the sensor ran for more than five months. Shwetha Sunil Kumar, a Ph.D. candidate in mechanical engineering, said the coating also made the sensors better at detecting formaldehyde. 

The team further found that by adding humidity to the sensor at the end of its life, it regained about 90% of its sensing ability.

Jayan is confident that these materials could be deployed to other devices to enhance lifetime and performance. She is currently developing similar technology to extend the life and safety of batteries.