Multizone Polymer Membrane for Dialysis
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Solution Overview
Problem
Current dialysis methods, such as hemodialysis and hemofiltration, face challenges in effectively removing small and medium-sized molecules from a patient's blood, particularly in home hemodialysis settings, where the complexity of water treatment systems and equipment installation deter frequent treatments, and existing membranes lack optimal combinations of convective and diffusive transport mechanisms.
Innovation Solution
Development of semi-permeable membranes with varying pore sizes along their length, achieved by exposing different portions of the membrane to distinct temperatures, allowing for a gradient of pore sizes that enables differential permeation of molecules, enhancing the removal of toxins and waste products.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single pore size membrane is used, then the structure is simple and easy to manufacture, but it cannot effectively remove both small and medium-sized molecules simultaneously
Solution Approach 1:
The membrane is divided into multiple zones along its length, with each zone having a different pore size. This segmentation allows different regions of the membrane to selectively remove different sized molecules, achieving both small and medium molecule clearance without requiring multiple separate membranes
Solution Approach 2:
Different portions of the membrane are given different local properties (pore sizes) to optimize their function. The first zone has larger pores for medium-sized molecules while the second zone has smaller pores for small molecules, allowing each region to perform its specialized function
2Reliability
If home hemodialysis equipment is installed with dedicated water treatment systems, then treatment quality can be maintained, but installation complexity and cost increase significantly
Solution Approach 1:
The membrane's pore size parameter is varied along its length to create zones with different molecular weight cut-offs. This parameter change allows a single membrane to perform functions that would traditionally require multiple membranes or complex filtration systems, simplifying the overall equipment requirements for home dialysis
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
The membranes effectively separate small and medium-sized molecules through a combination of convective and diffusive transport, improving the efficiency of dialysis treatments and making home hemodialysis more accessible by simplifying the treatment process and equipment requirements.
Implementation Method 1
Hemodialysis in general uses diffusion to remove waste products from a patient's blood. A diffusive gradient that occurs across the semi-permeable dialyzer between the blood and an electrolyte solution called dialysate causes diffusion.
Implementation Method 2
Hemofiltration is an alternative renal replacement therapy that relies on a pressure difference and thus a convective transport of toxins from the patient's blood.
Data Source
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AI summary
Membranes are made from polymers and heat treated so that they have at least two zones with pores of different sizes. Pores with a smaller size have a lower molecular weight cut off than pores with a larger size. Zones with pores of different sizes may also be made by coating portions of membranes with polymer coatings. Membranes with pores of different sizes may be used in dialyzers for hemofiltration, hemodiafiltration, and other hemodialysis procedures. The membranes may also be used in other separation processes.