Scientists have a new way to trap coronavirus particles: a liquid membrane that could reveal how much of the virus is in the air

• Scientists at the University of Maine are developing a liquid membrane that can trap coronavirus particles.
• The tool would allow them to analyze aerosol samples from a given space.
• From there, they could determine how much of the virus was spreading and whether it could have infected people.

Caitlin Howell isn't the first scientist to adapt her research to the coronavirus. Like many others, she saw an opportunity to use her laboratory to solve one of the pandemic's mysteries: in her case, the degree to which virus particles linger in the air.

Before the outbreak began, Howell's lab at the University of Maine developed liquid membranes designed to prevent bacteria from latching onto surfaces like the inside of a pipe or underside of a boat. Now, the lab is adapting those membranes to trap the coronavirus.

"These viruses are actually pretty fragile things when they're outside the human body," Howell said. "Inside, they do so much damage, but once they're outside, they're kind of wimpy."

Because the coronavirus dies easily on hard surfaces or in the air, Howell's team wants to install their membranes in front of air filters to trap particles while they're still alive. That way, they could perform a forensic-style analysis of how much virus is present in a given room.

"The goal is to be able to get the information of what was there and how dangerous it was," Howell said. That information, she added, could help answer important questions like how coronavirus aerosols travel across a room or how many aerosols a person needs to inhale to actually get infected.

Trapping the virus like an insect

Howell's membrane material is inspired by the pitcher plant: a vase-shaped plant with a thin layer of liquid along its rim. The liquid is slippery enough that when an insect lands on it, the bug goes sliding down to the belly of the plant, where it gets trapped in digestive fluid.

The membrane can collect live virus in a similar manner.

"You're catching them nicely in this liquid and protecting them in this liquid," Howell said. "Then you can remove them once you've stopped the filtration."

Studying coronavirus particles that linger in the air is crucial because a growing body of research suggests that when a person talks, coughs, sings, or even just exhales, virus-laden aerosols can linger in the air for several minutes. That can allow them to travel more than 6 feet away from an infected person. But scientists still aren't sure how much these aerosols play a role in transmission.

Part of the reason that's hard to study is that standard air filters, like those in schools or hospitals, kill the virus as they trap it. For airborne transmission to occur, these particles must remain infectious over time, but it's challenging for scientists to determine whether aerosols contain live virus in any particular situation.

That's where the liquid membrane comes in.

"The liquid is deformable, so that is what allows us to be actually very gentle with the viruses," Howell said, adding, "when you're filtering them and collecting them, you have to be really, really, really careful."

A recon mission for scientists

Howell's lab is outfitted with a chamber that simulates aerosols generated from coughing or sneezing. The team uses a vacuum pump to suck the aerosols across small liquid membranes about 2 inches in diameter. Howell said it's easier to quantify the amount of virus trapped within a small membrane, but her lab is capable of producing huge sheets of it as well.

Of course, there are challenges to working with an active virus inside a lab. For one thing, researchers don't want to expose themselves to hazardous particles. So for safety reasons, Howell's team plans to start working with dead coronavirus samples on August 1. After that, they'll graduate to a controlled facility that allows them to handle live samples.

Eventually, Howell said, they'll learn more about what types of environments favor airborne coronavirus transmission.

"We have proven that the concept works and now we're going to further develop it specifically for this virus," she said. "We would like to eventually design a system that could go anywhere, like travel hubs or hospital waiting rooms — places where you're worried about there being infectious material."

But these places would still require a filtration system or ultraviolet lights to remove harmful particles from indoor air.

"You might still want to use UV treatment because that will kill things," Howell said. "But when you kill things, then you lose that information about what was there and how dangerous it was."