Fig. 4: Pressure drop by filter.
From: Bioinspired capillary force-driven super-adhesive filter
a, Pressure drop curves during PM filtration. Error bars show s.d.; n = 3. b–e, Structures of captured PMs. Schematic of captured PMs on solid (b) and thin liquid-layered (d) filter media. The term teff represents the average distance from the fibre to the extremity of the PM accumulation. Optical microscope images of captured PMs, each with approximately 200 mg on bare (c) and PRO (e) metal meshes. The contour of pores is shown with a yellow line. f, Schematics of the PM screening by bare (left) and PRO (right) pre-filters for an HEPA filter. g, Weights of captured PMs on pre-filters and HEPA filters after the filtration test using the combinations of pre-filters and HEPA filters. Orange, blue and grey boxes indicate PMs on bare pre-filter, PRO pre-filter and HEPA filter. Error bars show s.d.; n = 3. The images on the right show the bare and PRO pre-filters after filtration with the HEPA filter. h, Photos of filters installed in the HVAC system; top right and bottom right are medium and pre-filters, respectively. i, Pressure drop difference across the HVAC system with bare (orange line) and PRO (green line) filters (26 May 2023 to 24 August 2023). Error bars show s.d.; n = 3. j, Electricity consumed by the fan of the HVAC systems for the same period operated with the bare (orange bar) and the PRO (green bar) filters. Error bars show s.d.; n = 3. Scale bars, 100 μm (c,e); 1 cm (g, right); 10 cm (h, right).
