Nanotech filter coating captures COVID-19 droplets

A physics professor from the University of Houston has developed a nanotech coating designed to allow air filters to capture airborne or aerosolized droplets of the virus that causes COVID-19.

The coating works by capturing liquids which encase the virus particles while still allowing air to flow through unimpeded. That allows ventilation systems to remove the virus during normal operation, without retrofitting or limiting the system’s ability to draw fresh air, said Seamus Curran, a physics professor known for his work commercializing nanotechnologies.

The coated filters are currently installed in one New York City public building.

Balancing filtration with air flow is critical to indoor air quality, a key issue as colder weather in some parts of the country pushes more people indoors.

Curran has worked with waterproof coatings, known as hydrophobic coatings, for almost a decade. The filter coating is a new water-based version designed to capture airborne virus particles, trapping them on the filter’s coating without limiting air flow.

He said the treated filters should be used in conjunction with other precautions, including masks and social distancing.

Last spring, Curran developed a coating for masks, but as more information emerged about how the virus is spread – traveling through respiratory droplets that can be small enough to drift on air currents – Curran turned his attention to air filters.

High-efficiency filters can also trap some virus particles, he said, but ventilation systems are designed to use specific types of filters; using a more highly rated filter can require changing or even replacing the ventilation system and would still require a number of passes through the ventilation system to be effective.

Curran said testing at an independent lab confirmed the treated filter captured the virus while, in comparison, it flowed through untreated filters of the same Minimum Efficiency Reporting Value, or MERV, rating. Water Lens currently is working on viral detection via wastewater.

In fact, Curran said, pollen and other particles that aren’t encapsulated in fluids – in the case of the coronavirus, usually saliva, phlegm and other respiratory fluids – still pass through the filter. “Our goal isn’t to change the rating of the filter,” Curran said, noting the MERV rating system reflects a filter’s ability to capture particles of varying sizes. “Filters are selected for the volume of the room they’re in. Our goal is to go after the virus. If we do, we can get people back into buildings in a safer environment and get the economy moving.

“We need science to help us get back to some form of normality, and we are happy to play our part.”

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