As the highly pathogenic H5N1 avian influenza continues to spread across the US, posing significant risks to dairy and poultry farms, farmers and public health experts urgently need better real-time monitoring tools to detect and respond to outbreaks. Researchers at Washington University in St. Louis have developed a new biosensor that can track airborne particles of H5N1.
Image Credit: Barillo_Images/Shutterstock.com
This new system offers a faster and more efficient way to monitor the virus. Their findings were recently published in a special issue of ACS Sensors focused on breath sensing.
To develop this bird flu sensor, Rajan Chakrabarty and his team at WashU’s McKelvey School of Engineering utilized electrochemical capacitive biosensors, enhancing the speed and sensitivity of virus and bacteria detection.
Their work comes at a critical time, as H5N1 has recently evolved to spread via airborne transmission, affecting mammals—including humans. The virus has already proven deadly in cats, and at least one human fatality has been reported.
“This biosensor is the first of its kind,” said Chakrabarty, referring to its ability to detect airborne virus and bacteria particles. Traditional detection methods, such as polymerase chain reaction (PCR) testing, are significantly slower.
Conventional tests can take over 10 hours—far too long to stop an outbreak effectively. In contrast, this new biosensor delivers results in just five minutes while also preserving microbial samples for further analysis. It provides real-time pathogen concentration data from farm environments, allowing for immediate response measures, Chakrabarty explained.
When the team first began this research, H5N1 was primarily transmitted through direct contact with infected birds. However, as their work progressed, so did the virus—mutating to become airborne.
The US Department of Agriculture’s Animal and Plant Health Inspection Service (APHIS) tracks farm-related outbreaks, with recent reports indicating at least 35 new dairy cattle cases of H5N1 across four states, mainly in California. “The strains are very different this time,” Chakrabarty noted.
If farmers suspect an infection, they typically send samples to state agricultural labs for testing, but the process can be slow, especially as case numbers surge. Current mitigation strategies include strict biosecurity measures such as quarantining animals, sanitizing facilities, and, in severe cases, mass culling. The USDA recently issued a conditional license for an avian flu vaccine, which could offer poultry farmers some relief and help stabilize egg prices.
How It Works
Designed to be portable and cost-effective for mass production, the biosensor integrates pathogen sampling and sensing into a single unit about the size of a desktop printer. It can be installed near farm ventilation systems, where it continuously collects and analyzes air samples.
At the heart of the system is a “wet cyclone bioaerosol sampler,” originally developed for detecting SARS-CoV-2 aerosols. It operates by drawing in air at high velocities and mixing it with a fluid lining the sampler’s walls, trapping virus particles. An automated pump then transfers the collected sample every five minutes to the biosensor for seamless detection.
Chakrabarty’s team, including senior staff scientist Meng Wu and graduate student Joshin Kumar, optimized the biosensor’s electrochemical surface to enhance sensitivity and stability, enabling the detection of virus concentrations as low as 100 RNA copies per cubic meter of air.
The sensor employs aptamers—single DNA strands that bind to viral proteins—to identify H5N1. The challenge was integrating these aptamers onto a bare carbon electrode surface, a task the team overcame by modifying the carbon with graphene oxide and Prussian blue nanocrystals. They credit their breakthrough to a key crosslinker, glutaraldehyde, which effectively “functionalized” the electrode for virus detection.
One major advantage of this detection method is its non-destructive nature. Unlike traditional tests that consume the sample, this biosensor allows samples to be preserved for further PCR analysis if needed.
The device is designed for ease of use—operators do not need biochemistry expertise to run it. It provides real-time virus concentration data, alerting farmers to potential outbreaks before they escalate. This ability to detect a range of pathogen concentrations is a major breakthrough in sensor technology and could be expanded to track multiple viruses and bacteria within a single device.
Chakrabarty concluded, “This biosensor is specific to H5N1, 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. We have demonstrated these capabilities of our biosensor and reported the findings in the paper.”
The team is now working to commercialize the biosensor.
St. Louis-based biotech company Varro Life Sciences has been consulting with the researchers to explore potential commercial applications. With its affordability, scalability, and ease of use, this biosensor could become a game-changer for disease monitoring in agricultural settings and beyond.
Journal Reference:
Kumar, J. et. al. (2025) Capacitive Biosensor for Rapid Detection of Avian (H5N1) Influenza and E. coli in Aerosols. ACS Sensors. doi.org/10.1021/acssensors.4c03087