A Microfluidic-Free Droplet Technology for Rapid and Quantitative Airborne Pathogen Monitoring

Pathogen transmission via indirect routes such as fomite, waterborne, and airborne transmission are hallmarks of both endemic and pandemic spread. Viruses such as Influenza, SARS-CoV-2, and measles are notable examples, in addition to deadly microbes such as Bordetella pertussis, Mycobacterium tuberculosis, and Coccidioides species. However, the rapid detection and analysis of airstreams as part of biosurveillance, public health monitoring, or epidemiological research remains challenging. Current state-of-the-art methods rely on bulky apparatuses for both the collection and detection of airborne agents; most of these methods are ill suited to rapid response point-of-testing within medical facilities, workplace locals, or public spaces. Further, these technologies are based on bulk Polymerase Chain Reaction (PCR) and Loop-mediated isothermal amplification (LAMP) methods that have limited quantitative accuracy. Thus, more portable and accurate platforms are needed to address the types of rapid response and ubiquitous monitoring that is required to minimize outbreaks in the 21st century. Towards this objective, this grant will address the need for an improved method of airborne pathogen detection through the development of the digital droplet Aerosol Capture & Quantification (ddACQ) system. The ddACQ system consists of two novel technologies, a filter particle array and a droplet buoyancy counter. The filter particle array allows for the capture of airborne pathogens or biological agents and generation of microfluidic droplets when mixed with an oil and water reagent solution. A phone-powered heat block then drives a one-step isothermal digital droplet reaction. Digital techniques have several key advantages over classical quantitative PCR and LAMP techniques, namely single molecule detection and direct quantification without a standard curve. Finally, the droplet buoyancy counter allows for smartphone based read out of the reaction immediately at the testing site in under an hour. Together, the innovations within and implementation of the ddACQ system represents a novel application of microfluidic principles and an enabling technology for both pathogen transmission research and public health monitoring applications. Project Number: 1R21AI196878-01 | Fiscal Year: 2026 | NIH Institute/Center: National Institute of Allergy and Infectious Diseases (NIAID) | Principal Investigator: Daniel Weisgerber | Institution: UNIVERSITY OF CALIFORNIA, SAN FRANCISCO, SAN FRANCISCO, CA | Award Amount: $451,000 | Activity Code: R21 | Study Section: Enabling Bioanalytical and Imaging Technologies Study Section[EBIT] View on NIH RePORTER: https://reporter.nih.gov/project-details/1R21AI19687801