A lottery draw machine-inspired movable air filter with high removal efficiency and low pressure drop at a high flow rateElectronic supplementary information (ESI) available: Images of spherical MFS/NPs with various sizes, SEM images of CaCO3 precipitates and Ag/Pt/Pd precipitates, images showing delivery of PM-laden polluted air by air flow, images showing the air filtration system containing different sized (volume) spheres, images showing the electrostatic effects of MAFs and the PM2.5 remova

A lottery draw machine-inspired novel movable air filter (MAF) system is presented in which MAFs are vigorously moved or rotated to generate a high electric field and capture particulate matter (PM) particles. The MAF system purified 500 mL of a hazardous level of PM particles (2016 μg m −3 PM 10 and 1040 μg m −3 PM 2.5 ) at a high flow rate of 2.5 m s −1 with high removal efficiencies (99.7% and 98.8% for PM 10 and PM 2.5 , respectively) in 1 min. The MAF system also had a small pressure drop of 3-6 Pa, which was approximately an order or orders of magnitude lower than previously reported values, even at a high flow rate of an order of magnitude higher than previously reported values. The MAF system exhibited excellent recyclability of up to 300 cycles with high removal efficiencies (99.7-98% and 98.8-96.2% for PM 10 and PM 2.5 , respectively). Furthermore, the MAF system could effectively remove 500 mL of PM particles at extremely high concentrations (over 10 000 μg m −3 PM 10 and over 3000 μg m −3 PM 2.5 ) with very high efficiencies (over 99.8% and 99.6%, respectively) and a very low pressure drop (6 Pa), and these properties led to the conversion to clean ambient air (24 μg m −3 PM 10 and 12 μg m −3 PM 2.5 ) in 15 min. A lottery draw machine-inspired novel movable air filter (MAF) system is presented in which MAFs are vigorously moved or rotated to form a high electric field and capture particulate matter (PM) particles.