Parallel Membrane Pumps for Hemodialysis Mode Switching
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Solution Overview
Problem
Existing disposable blood treatment systems for hemodialysis face challenges in seamlessly switching between single-needle (SN) and double-needle (DN) operations, leading to complications such as clogging, blood leakage, and hemolysis, and require complex machinery with dedicated pneumatic or hydraulic systems.
Innovation Solution
A disposable blood treatment system with parallel membrane pumps that use treatment fluid for operation, allowing for simple and efficient switching between SN and DN modes by controlling the timing of pump phases and using hydraulically controlled valves to manage blood flow, reducing the need for complex machinery and minimizing mechanical interfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a disposable blood treatment system uses parallel membrane pumps with treatment fluid for operation, then the system achieves simplified design and silent operation, but requires precise timing control of pump phases
Solution Approach 1:
The patent uses treatment fluid (dialysate) as a hydraulic medium to simultaneously operate multiple membrane pumps and control valve positioning. The fluid pressure generated by one pump is transmitted through fluid communication channels to control the phases of other pumps and the position of control valves, eliminating the need for separate pneumatic or electrical control systems.
Solution Approach 2:
The system is designed so that the treatment fluid itself serves as the control medium for the pump arrangement. The pumps and valves automatically coordinate their operation through fluid pressure transmission without requiring external control machinery, achieving self-regulated phased operation.
2Ease of operation
If the system uses hydraulically controlled valves to manage blood flow, then switching between SN and DN modes becomes efficient, but the system requires minimal mechanical interfaces
Solution Approach 1:
Control valves are designed with hydraulic actuation where treatment fluid pressure directly controls valve opening and closing. The valves respond to pressure changes from the membrane pumps to automatically route blood flow between single-needle and double-needle configurations without mechanical linkages or complex control mechanisms.
Solution Approach 2:
The control valves serve multiple functions by being controlled through a single hydraulic system. The same treatment fluid that drives the pumps also controls all valve positions, allowing one control mechanism to manage multiple flow paths and operational modes.
3Reliability
If the system reduces complex machinery and mechanical interfaces, then the risk of clogging and hemolysis decreases, but the system requires reliable fluid communication between pumps
Solution Approach 1:
The system uses fluid communication channels to transmit pressure signals between pumps and to control valves. This hydraulic linkage eliminates the need for mechanical connections that could introduce contaminants or cause hemolysis, while the smooth fluid pathways are designed to prevent clogging.
Solution Approach 2:
The membrane pumps use flexible membranes to separate treatment fluid and blood compartments while allowing pressure transmission. These thin film barriers prevent direct contact between control fluid and blood, eliminating contamination risks while maintaining reliable pressure-driven operation.
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 system achieves reliable operation with reduced risk of clogging and hemolysis, silent operation, and simplified design, enabling efficient blood flow management in both SN and DN modes without the need for complex pneumatic or hydraulic systems.
Implementation Method 1
Each membrane pump comprises a pressure chamber, which is controlled to expand or compress by being alternately filled and emptied of a gas or a liquid
Implementation Method 2
electromagnetically or pneumatically actuated control valves on both sides of the pressure chamber to control the direction of the blood flow generated by the pressure chamber
Implementation Method 3
a dialyzer with an inlet connected to a feed line and an outlet connected to a return line
Data Source
Figure 1~2B
Figure 3A~5B
Figure 6~7B
AI summary
A disposable for use in blood treatment comprises a blood treatment unit (8) and a pump arrangement (11) operable to pump blood through the blood treatment unit (8). The pump arrangement (11) comprises two membrane pumps (6, 7) connected in parallel on one side of the blood treatment unit (8). The disposable is operable in a single-needle mode, in which the pump arrangement (11) is operable to generate a pulsatile flow of blood through the blood treatment unit (8), and in a double-needle mode, in which the pump arrangement (11) is operable to generate an essentially continuous flow of blood through the blood treatment unit (8). The pump arrangement (11) is configured for connection to a supply system (1) of treatment fluid for the blood treatment unit (8) such that alternating flows of treatment fluid generated by the supply system (1) and supplied to the first and second membrane pumps (6, 7) causes the pump arrangement (11) to generate the desired flows of blood in the single-needle and double- needle modes. The treatment fluid may be used as motive fluid for displacing the blood in the membrane pumps (6, 7) and/or as control fluid for controlling opening and/or closing of upstream and downstream commutation valves (34, 35) in the membrane pumps (6, 7).