Reciprocating Pod Pump Geometry for Low-Shear Blood Heating
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Centrifugal pumps used in extracorporeal heating systems apply high shear forces to blood, leading to hemolysis, and are cumbersome, causing setup time lags and increasing the risk of improper setup, especially when switching between patients.
Innovation Solution
A reciprocating positive-displacement pump with a hemispherical rigid chamber and a flexible membrane that imparts low-shear flow, using a silicone membrane with bumps to reduce shear forces and turbulence, and a system of pumps and valves to manage fluid flow efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If centrifugal pumps are used to achieve high flow rates, then productivity is improved, but object-affected harmful factors worsen due to high shear forces causing hemolysis
Solution Approach 1:
The pump is divided into multiple lobes (typically three) that independently move fluid around the periphery of the pumping chamber. This segmentation allows each lobe to create a separate flow path, reducing turbulence and shear forces while maintaining high flow rates through coordinated operation of multiple lobes.
Solution Approach 2:
The pump employs a spherical or near-spherical pumping chamber with curved surfaces instead of sharp edges or angles. The lobes themselves are curved, and the chamber geometry is optimized with rounded contours to guide fluid flow smoothly around the periphery, minimizing turbulence and shear forces on the blood while maintaining efficient fluid movement.
2Productivity
If centrifugal pumps are used for rapid patient transitions, then productivity is improved, but device complexity worsens due to cumbersome setup procedures
Solution Approach 1:
The pump is designed as a disposable single-use device that is pre-packaged in sterile condition. After one patient treatment, the entire pump is discarded and replaced with a new sterile unit for the next patient. This eliminates complex cleaning, sterilization, and setup procedures between patients, enabling rapid transitions while reducing the risk of improper setup or contamination.
Solution Approach 2:
The pump is designed with universal connection interfaces that can be quickly attached to standard medical tubing and equipment. The device integrates multiple functions including pumping, flow control, and patient connection in a single compact unit, simplifying the overall system setup and reducing the number of separate components that need to be assembled during patient transitions.
3Productivity
If high flow rates are used for extracorporeal heating, then productivity is improved, but object-affected harmful factors worsen due to hemolysis from shear forces
Solution Approach 1:
The segmented lobe design creates multiple independent flow paths around the pumping chamber periphery, distributing the high flow rate across several gentle flow streams rather than a single high-velocity stream. This maintains the productivity needed for efficient heating while reducing the shear forces and turbulence that cause hemolysis.
Solution Approach 2:
The spherical pumping chamber geometry with curved surfaces guides fluid flow in smooth arcs around the periphery, eliminating sharp edges, angles, or sudden direction changes. This curved geometry maintains efficient fluid movement for heating while minimizing turbulence and shear forces that would damage red blood cells.
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 system effectively reduces hemolysis and improves setup efficiency by minimizing shear forces and turbulence, ensuring safe and rapid patient transitions while maintaining fluid flow control.
Implementation Method 1
a pressure gradient is created across the membrane by applying a positive or negative pressure to the actuation chamber
Implementation Method 2
a flexible membrane attached to the rigid chamber wall, so that the flexible membrane and rigid chamber wall define a pumping chamber
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).