Reciprocating Pod Pump Geometry for Low-Shear Blood Flow
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Solution Overview
Problem
Centrifugal pumps used for high flow rates in extracorporeal heating systems create significant shear forces on blood, leading to hemolysis, and are bulky and cumbersome, posing risks of leaks and setup errors.
Innovation Solution
A reciprocating positive-displacement pump with a hemispherical rigid chamber and flexible membrane design, featuring tangential flow directions and a spaced outlet, reduces shear forces and includes features like silicone membranes and bumps to minimize hemolysis, along with a system for independent pump operation and control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If centrifugal pumps are used to achieve high flow rates, then productivity is improved, but shear forces on blood increase causing hemolysis
Solution Approach 1:
The pump is divided into multiple chambers (first chamber, second chamber, third chamber) with separate pumping elements that operate in sequence. This segmentation allows the blood flow to be divided into multiple smaller streams, reducing the shear forces on individual blood cells while maintaining high overall flow rate through parallel processing of multiple fluid streams.
Solution Approach 2:
The invention employs curved and spherical geometries in the pump chambers and flow paths. The blood is directed through curved pathways rather than sharp angles, and spherical pumping elements are used to create smooth, continuous flow patterns. This spheroidality reduces turbulence and shear forces on blood cells while maintaining efficient fluid transport.
2Productivity
If centrifugal pumps are used for high flow rates, then productivity is improved, but device complexity and bulkiness increase leading to leak risks and setup errors
Solution Approach 1:
Multiple pumping chambers and functions are merged into a single integrated pump unit. The first, second, and third chambers are combined in one device with shared structural components, reducing the overall bulkiness compared to using multiple separate centrifugal pumps. The merging of functions into a compact modular design simplifies setup procedures and reduces the risk of assembly errors.
Solution Approach 2:
The pump employs movable partitions and flexible membranes that dynamically adjust the chamber volumes during operation. This dynamic mechanism allows the pump to achieve high flow rates through coordinated expansion and contraction of chambers, eliminating the need for large, bulky stationary components while maintaining efficient fluid transport capability.
3Productivity
If high flow rates are achieved through conventional pumps, then productivity is improved, but the risk of leaks and setup errors increases
Solution Approach 1:
The pump incorporates self-priming capability and automatic air elimination through the sequential operation of its chambers. The coordinated expansion and contraction of the first, second, and third chambers creates natural suction and pressure differentials that eliminate the need for complex external priming systems, reducing setup steps and potential failure points. The design inherently manages fluid levels and prevents air locks through its chamber sequence.
Solution Approach 2:
The pump design includes built-in pressure equalization chambers and flexible membranes that compensate for pressure variations before they can cause leaks. The sequential operation of multiple chambers creates buffered pressure transitions, preventing sudden pressure spikes that could compromise seals or connections. This beforehand cushioning of pressure changes enhances reliability during high-flow 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 pump design significantly reduces shear forces on fluids, minimizing hemolysis and improving safety by reducing bulkiness and setup time, while allowing for efficient and controlled fluid handling.
Implementation Method 1
a pump for pumping a fluid from a first location to a second location, the pump comprising: a pumping chamber; a flexible membrane forming part of the pumping chamber; an actuation chamber; and a controller. The controller is configured to: determine that a threshold condition has been satisfied, wherein the threshold condition relates to an operating parameter of the pump; and in response to determining that the threshold condition has been satisfied, vary a pressure in the actuation chamber to cause the flexible membrane to reciprocate
Implementation Method 2
The pump design significantly reduces shear forces on fluids, minimizing hemolysis and improving safety by reducing bulkiness and setup time
Data Source
AI summary
Embodiments of the present invention relate generally to certain types of reciprocating positive-displacement pumps (which may be referred to hereinafter as “pods,”“pump pods,” or “pod pumps”) used to pump fluids, such as a biological fluid (e.g., blood or peritoneal fluid), a therapeutic fluid (e.g., a medication solution), or a surfactant fluid. The pumps may be configured specifically to impart low shear forces and low turbulence on the fluid as the fluid is pumped from an inlet to an outlet. Such pumps may be particularly useful in pumping fluids that may be damaged by such shear forces (e.g., blood, and particularly heated blood, which is prone to hemolysis) or turbulence (e.g., surfactants or other fluids that may foam or otherwise be damaged or become unstable in the presence of turbulence).