Fig. 3: Harvesting and treating contaminated fog with nanoengineered reactive meshes.

a, Schematic showing the laboratory-scale fog harvesting setup used to generate contaminated fog (containing methyl orange) at an initial concentration C₀, along with the fog harvesting and treatment, and measurement of the final concentration (C) of methyl orange. Φ, is the fog tunnel diameter. b, Micrograph showing a single unit cell of the mesh (stainless steel), where R is the radius of the mesh wire and 2G is the wire spacing. Scale bar, 0.4 mm. c, Colour image sequence showing the mesh surfaces during fog harvesting experiments in the presence (C₀ = 25 ppm) and absence (C₀ = 0 ppm) of contaminated fog. The control experiments used uncoated meshes, and the reactive coatings TiO₂-PVB-PDMS and TiO₂-EC-PDMS were used after UV irradiation. The dashed white box indicates the region where the intensity of the colour blue, Ī_b, was measured (aqueous methyl orange absorbs blue light⁵⁷); the box ___location varies since the droplet–mesh interaction is different in each case. Before the fogging starts, the value of Ī_b for the window is normalized and set to unity. Scale bar, 0.4 mm. d, Quantifying the effect of C₀ on the ability of the mesh coating to treat the intercepted fog: uncoated mesh (green bar), TiO₂-PVB-PDMS reactive mesh (blue bar) and TiO₂-EC-PDMS reactive mesh (red bar). The bar represents the mean value for n = 15 experiments and the data distribution is shown by the black dots. C was measured at t = 66 min; fog harvesting experiments were started at t = 0 min. For all runs, the fog velocity was kept constant (v_fog = 1.5 m s⁻¹).