Investigation of membrane fouling at the microscale using isopore filters

Investigations of membrane fouling at the pore-scale have long been of limited interest due to microstructural defects of the commercial membranes that prevent any quantitative analysis of the experimental results. In this paper, we employed novel microengineered membranes with regular pore size to investigate the effect of the membrane pore geometry on the fouling mechanisms during filtration of micron-sized particles. For particles larger than the membrane pore size, the fouling mechanism was pore blockage followed by the cake filtration, while pore narrowing was the dominant mechanism when particles were smaller than the membrane pore size. Filtration with the slotted pore membrane offers some interesting advantages comparing to the filtration with circular pores. The rate of flux decline was slower for the membrane with slotted pores compared with the membrane with circular pores since the initial particle deposition only covered a small fraction of the pores. It was also found that the flow resistance of the slotted pore membrane is much lower than the circular one because a slotted pore has a smaller perimeter than several circular pores with the same total surface area. We can conclude that by proper selection of membrane pore geometry, flux decline can be hindered while maintaining a high selectivity during microfiltration. These findings can be useful also for researchers who are using microfluidic platforms with integrated isopore filters for various applications such as stem cell enrichment, cancer cell isolation, blood fractionation and pathogen removal.