Fig. 9. Separating the OWM by using the fs laser-structured porous PTFE sheet. (a and b) Surface morphology of the rough porous sheet. (c) Optical microscope image of the as-prepared sheet. The sample was irradiated by a beam of white light from its backside. (d and e) Continuously dripping oil droplets onto the rough porous PTFE sheet: (d) oil droplets wetting and penetrating through the sheet, (e) the penetrated oil dropping down. (f–h) Process of separating the mixture of water (blue color) and oil (red color): (f) before separation, (g) pouring the mixture into the separating device, (h) after separation. Reproduced from ref. 16 with permission from Elsevier, copyright 2016.