Integrated five-stage cascade impactor with MIP-modified QCM sensor for real-time monitoring of airborne microorganisms

Pathogens present a significant threat to global public health, necessitating the development of rapid and reliable detection methodologies for effective monitoring and outbreak management. This study introduces a new sensing device that uses molecularly imprinted polymer (MIP) for sensitive and specific Staphylococcus aureus detection. The research presents a comprehensive investigation into the design and optimization of a five-stage Sioutas Cascade Impactor (SCI) integrated with quartz crystal microbalance (QCM) sensing, enabling continuous, size-resolved collection and in situ monitoring of airborne bacteria. The study combines theoretical modeling of particle impaction dynamics with empirical evaluations of sampler collection efficiency, pressure drop characteristics, and sensor surface properties. A key focus is the optimization of flow control, along with a rigorous evaluation of MIPs as biosensing coatings on QCM sensor. For this purpose, in situ chemical polymerization of dopamine was conducted in the presence of S. aureus bacteria. To confirm surface modification, various microscopic and spectroscopic analyses were employed. Results demonstrate that careful control over flow conditions (14.6 min of sampling time and a flow rate of 6.96 L/min) and resulting pressure gradients, together with MIP surface functionalization, is crucial for achieving high bacterial capture. This work establishes a robust framework for the development of real-time, reusable biosensors for proactive airborne pathogen surveillance.