New Transparent Coating Captures Airborne Droplets

A 3D microscopic view of captured droplets. Image courtesy of Northwestern University.

Researchers at Northwestern University (Evanston, Illinois, USA) have developed a new transparent coating material that is able to capture droplets and aerosols, effectively removing them from the air. According to the university, this material is a more effective antiviral solution than plexiglass barriers that deflect droplets, causing them to bounce away but remain in the air.

This clear, viscous liquid coating can be painted onto any surface, including plastic glass, wood, metal, stainless steel, concrete and textiles. Droplets that collide with the coated surface stick to it, get absorbed, and then dry up.

“Droplets collide with indoor surfaces all the time,” says Jiaxing Huang, a professor of materials science and engineering in Northwestern’s McCormick School of Engineering and the study’s senior author. “Right now, plexiglass dividers are deviating devices; they deflect droplets. If a surface could actually trap droplets, then every single droplet effectively removed from indoor air would be a successful elimination of a potential source of transmission.”

The coating is also compatible with antiviral and antimicrobial materials, so sanitizing agents such as copper could be added to the formula. The research team, which includes members of Huang’s laboratory, found that the coated surfaces captured three times more aerosol droplets than uncoated surfaces — even when they were bombarded with aerosol droplets in highly concentrated doses that were atypical for an indoor environment.

Huang’s team embarked on this project during the stay-at-home order at the beginning of the COVID-19 pandemic. The main component in their coating material is a polyelectrolyte polymer that is commonly used in a wide variety of cosmetic products. When applied with a blade or brush, the resulting formula yields uniform and conformal coatings on a broad range of indoor surfaces without damaging or discoloring the original material.

In addition, the team found that even when doused with droplets, the surfaces remained transparent and haze-free—or to put it another way, they did not appear filthy or soiled. If used on plexiglass barriers, those coated barriers would not need to be cleaned more frequently than uncoated barriers.

Due to the versatility of the coating, Huang believes that it could be used on plexiglass barriers and face shields, as well as on no-touch or low-touch surfaces such as walls or curtains.

“There are massive areas of indoor surfaces that are barely touched by people or pets,” says Huang. “If we repurposed these ‘idling’ surfaces to capture respiratory droplets, then they could become functional ‘devices’ to help reduce air-borne transmission of infectious diseases.

“Surface-trapped pathogens can then be readily inactivated over time, which can be accelerated by pre-applied sanitization ingredients,” he adds. “They also can be removed during routine cleaning.”

The study, “Droplet-capturing coatings on environmental surfaces based on cosmetic ingredients,” was recently published in Chem, a scientific journal published by Cell Press.

Source: Northwestern Now,