Egg prices in the US have reached yet another record as one of the worst avian flu outbreaks in history continues to unfold. Across the country, bakers and shoppers scrambled to find alternatives as avian influenza swept through poultry and dairy farms, pushing up egg prices.
This outbreak, like others before it, caught us unprepared. But in a laboratory at Washington University in St. Louis, a team of engineers is preparing a response.
“This biosensor is the first of its kind,” said Rajan Chakrabarty, a professor of energy, environmental, and chemical engineering at Washington University.
His team has created a compact, portable system that can detect airborne particles of the deadly H5N1 bird flu virus within five minutes.
Why this is so important
Chakrabarty’s lab didn’t originally set out to fight avian flu. The technology began as an air sampler for detecting SARS-CoV-2 particles. But as avian influenza began leaping from birds to mammals—and in some cases, to humans—the team pivoted quickly.
“As this paper evolved, so did the virus; it mutated,” said Chakrabarty.
The researcher realized that conventional test methods for the avian flu took more than 10 hours. That’s just too long to stop an ongoing outbreak. The avian flu situation has also escalated dramatically.
That mutation has proven deadly in cats, and earlier this year, the U.S. reported at least one human death from H5N1. Since April 2024, more than 90 million birds have been affected, and 70 human cases have been confirmed in the United States, according to the Centers for Disease Control and Prevention.
The U.S. Department of Agriculture (USDA) recently reported fresh cases in dairy cattle across four states, predominantly in California. And while the CDC still considers the immediate risk to the general public low, the virus’s airborne transmission has made farmers and public health officials uneasy.
Simply put, the avian flu had become a major problem. So Chakrabarty and colleagues set out to design a better detector.
A box to detect the flu
The team’s solution is both elegant and practical. The machine, about the size of a desktop printer, is meant to sit near farm ventilation systems and continuously sample the air. Inside, it uses a “wet cyclone bioaerosol sampler”—a chamber that spins incoming air at high speeds, causing viral particles to collide with and stick to fluid-coated walls.
That fluid is then pumped automatically to an electrochemical biosensor every five minutes. And here’s where the diagnosis actually happens.
Graduate student Joshin Kumar and senior staff scientist Meng Wu spent months fine-tuning the tiny electrode surface of the biosensor. Their goal was to detect trace amounts of viral RNA—less than 100 copies per cubic meter of air.
The biosensor uses “capture probes” called aptamers. These are essentially single strands of DNA that bind to virus proteins, flagging them. It took months of tweaking and trial-and-error to see how this system could be optimized. They coated the carbon electrode with graphene oxide and Prussian blue nanocrystals, enhancing its ability to conduct electricity and bind to viral markers. Then, using a linking molecule called glutaraldehyde. With this, they managed to anchor single strands of DNA—aptamers—that specifically attach to virus proteins.
That combination, Kumar explained, is the “secret sauce” behind the sensor’s precision and sensitivity. When an aptamer binds to an H5N1 virus particle, it triggers an electrical signal, confirming the virus’s presence and concentration.
From lab to barn
As complex as the sensor itself is, it’s actually simple to operate. Unlike bulky lab instruments, the components are also affordable and scalable. The team is already working with Varro Life Sciences, a St. Louis biotech firm, to commercialize the device.
Importantly, the detection process is nondestructive. This means that once a sample is tested, it can still be sent for conventional lab analysis, such as PCR, providing a backup for confirmation and further study. So if a farmer is concerned about a sample, they could also get a confirmation
There’s another bonus: the design could be tweaked for other types of pathogens.
“This biosensor is specific to H5N1,” said Chakrabarty. “But it can be adapted to detect other strains of influenza virus (e.g., H1N1) and SARS-CoV-2 as well as bacteria (E. coli and pseudomonas) in the aerosol phase.”
However, whether the sensor can work long-term in a rough farm environment is less clear. Farm air is often filled with dust, moisture, and all sorts of organic particles that could affect the sensor’s accuracy. The next step is for the sensor to start being used in practical environments.
Even if it does work, however, the current influenza outbreak is likely too widespread for it to make a difference. Ideally, you’d have a robust sensor array in place before the outbreak becomes established. In this scenario, tools like Chakrabarty’s device could become the frontline in detecting—and preventing—future outbreaks.
To contain the current avian flu outbreak, widespread early detection systems like portable biosensors are important. In addition, we’d need rapid response protocols on farms, and coordinated global surveillance to stop the virus before it spreads across species and truly makes its way to humans.
Journal Reference: Joshin Kumar et al. Capacitive Biosensor for Rapid Detection of Avian (H5N1) Influenza and E. coli in Aerosols. ACS Sensors, 2025; DOI: 10.1021/acssensors.4c03087
