Porous Membrane Surface Control for Low-Fouling Cell Broth Filtration
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Solution Overview
Problem
The permeation rate of products through porous membranes used in continuous cell culture systems decreases due to fouling, which occurs as substances deposit on the membrane surface and micropores, leading to inefficiencies in the filtration process.
Innovation Solution
The use of porous membranes with specific surface characteristics, such as an opening ratio of 57.5% or less, pore diameter coefficient of variation of 0.5 or less, and structural anisotropy of 0.97 or more and 1.03 or less, along with controlled shear stress of 4.0 N/m2, to maintain membrane permeability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a porous membrane is used to separate cells from cell broth in continuous culture, then cells can be continuously separated and culture medium can be supplied, but fouling occurs over time causing decrease in membrane permeability
Solution Approach 1:
The patent applies parameter changes by precisely controlling the opening ratio (50-80%), pore diameter (0.01-10 μm), and pore size distribution (coefficient of variation 0.3-2.0) of the porous membrane to optimize filtration performance while minimizing fouling. By adjusting these physical parameters, the membrane maintains stable permeability during continuous operation
Solution Approach 2:
The patent applies local quality by creating membranes with non-uniform pore structures, where different regions of the membrane have different pore sizes and distributions. This allows optimized filtration at the surface while maintaining structural integrity and resistance to fouling in deeper layers
2Productivity
If high cell density is maintained in continuous culture, then production efficiency increases, but fouling on the membrane surface accelerates
Solution Approach 1:
The patent controls the opening ratio and pore diameter parameters to match the size and concentration of cells in high-density cultures, allowing efficient separation while preventing excessive fouling. The specific pore size range (0.01-10 μm) enables filtration at high cell densities without rapid membrane clogging
Solution Approach 2:
The patent converts the potentially harmful effect of high cell density (which causes fouling) into a beneficial condition by designing the membrane to handle these conditions. The controlled pore structure allows the membrane to withstand high cell densities without significant performance degradation, turning what would be a harmful factor into an acceptable operating condition
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively suppresses the decrease in permeation rate, ensuring efficient and stable production and purification of products like antibodies by maintaining optimal membrane performance.
Implementation Method 1
filtering a cell broth through a porous membrane to obtain a product by the cells
Implementation Method 2
a shear stress due to a flow of the cell broth on the liquid contact surface is set to 4.0 N/m2 or less
Data Source
AI summary
There is provided a method for producing a product by cells, the method including filtering a cell broth through a porous membrane to obtain a product by the cells, in which the porous membrane has a liquid contact surface having at least any one selected from the group consisting of an opening ratio of 57.5% or less, a pore diameter having a coefficient of variation of 0.5 or less, and a ratio of pore diameter/fiber diameter of 1.3 or less, and the liquid contact surface has at least any one selected from the group consisting of a structural anisotropy of 0.97 or more and 1.03 or less and a ratio of long pore diameter/short pore diameter of 1.8 or less, and a shear stress due to a flow of the cell broth on the liquid contact surface is set to 4.0 N/m2 or less.