Acoustic energy boosts air purification: A novel sound-wave drive TENG for filterless particulate capturing

Maintaining good indoor air quality is crucial for human health, as poor air quality in enclosed spaces can elevate the risk of infection and cause premature deaths. This study introduces a novel low-cost, filter-less method for capturing ultrafine particulates to improve air purification efficiency in air ductworks. The new technology employs sound waves to cluster particulates and simultaneously activate triboelectric nanogenerators (TENGs) to operate as electrostatic precipitators, creating a synergistic approach where two techniques complement and enhance each other. The sound waves, created within a U-shaped acoustic resonating chamber using loudspeakers, cluster the particulates and excite the TENG to generate high electrical fields between its electrodes. This high electrical field captures the clustered particulates by electrostatic precipitation. Experimental tests are utilized in this work. The peak electrical output of the electrospun nanofiber-based TENG was recorded at approximately 60 V (peak-to-peak value) in the presence of sound fields. In addition, we fabricated a scaled-down ventilation model to examine the efficiency of particle filtration. Experimental results show that this technique significantly improves the removal efficiency, particularly for ultrafine particulates (0.3–1.0 µm). The maximum removal efficiency for PM_2.5 can reach 97.5 %, comparable to that of HEPA filters. The findings of this work demonstrate the effectiveness and controllability of this novel filter-less air purification method.