Non-Contact Ultrasonic Inspection of Filtration Membranes Using Air-Coupled PMUT

Industry 5.0 emphasizes smart, connected systems, integrating MEMS-based sensors, IoT, and AI to enable advanced, real-time monitoring solutions. In this study, we present a non-contact, non-destructive ultrasonic inspection method for filtration membranes using air-coupled piezoelectric micromachined ultrasonic transducers (PMUTs) suitable to be deployed in the fabrication line for in-line and real time testing of the production. Filtration membranes play a critical role in respiratory protection and ventilation systems, where ensuring consistent performance—measured via particle filtration efficiency (PFE) and pressure resistance—is essential. We designed and fabricated a novel 200 kHz PMUT array optimized for air-coupled through-transmission measurements of porous materials. Experimental validation was performed on different meltblown polypropylene membranes.. The PMUT results were benchmarked against a broadband air-coupled ultrasonic transducer. The transmission coefficient measured by the PMUT array demonstrated sensitivity sufficient to distinguish between membranes with different filtration properties. These findings suggest the feasibility of using PMUTs for rapid, high-precision quality assessment of filtration materials.