Tensioned Polymeric Membrane Fluid Cassette for Heat Exchange
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Solution Overview
Problem
Current patient temperature control systems for neuro ICU patients, such as intravascular heat exchange catheters and external pads, face challenges in efficiently exchanging heat due to limitations in heat transfer impedance and mechanical handling, particularly in maintaining membrane tension and reducing conductive path length between cold plates and working fluid.
Innovation Solution
A fluid cassette with a tensioned polymeric membrane assembly, where the membranes are biaxially stretched and held in tension within a frame, creating a narrow, rectilinear working fluid chamber that expands against cold plates for enhanced heat exchange, reducing the need for moving mechanisms and minimizing impedance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If traditional heat exchange systems use rigid structures or non-tensioned membranes, then structural stability is maintained, but heat transfer efficiency is reduced due to longer conductive path length and higher impedance
Solution Approach 1:
The membranes are pre-stretched and secured to the frame in tension before use, creating a pre-tensioned structure that eliminates the need for complex tensioning mechanisms during operation. This preliminary action maintains optimal heat transfer conditions while simplifying the overall device complexity.
Solution Approach 2:
The patent uses thin polymeric membranes (no more than two mils thick) stretched in biaxial tension to create a flexible yet stable heat exchange surface. This approach reduces conductive path length and thermal impedance while maintaining structural integrity through the tensioned configuration.
2Temperature
If membrane thickness is increased to maintain structural integrity, then membrane strength is improved, but heat transfer efficiency is reduced due to increased conductive path length
Solution Approach 1:
The patent employs extremely thin polymeric membranes (one to two mils thick) that are stretched in biaxial tension. The tensioning creates structural integrity and mechanical strength without requiring increased thickness, thereby minimizing conductive path length and maximizing heat transfer efficiency.
Solution Approach 2:
The membranes are pre-stretched and secured to the frame in tension before use, creating a pre-tensioned structure that eliminates the need for complex tensioning mechanisms during operation. This preliminary action maintains optimal heat transfer conditions while simplifying the overall device complexity.
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 configuration enhances heat transfer efficiency by reducing the conductive path length and impedance, allowing for effective temperature control with lower working fluid pump requirements and quieter, cost-effective operation, while maintaining membrane integrity and ease of handling.
Implementation Method 1
enhances heat transfer efficiency by reducing the conductive path length and impedance
Implementation Method 2
the space between the membranes is expandable when filled with working fluid circulating from the heat exchange member
Data Source
AI summary
A working fluid cassette for an intravascular heat exchange catheter includes a frame holding two closely spaced, square polymeric membranes in tension. Working fluid from the catheter is directed between the membranes. The cassette is closely received between two refrigerant cold plates to exchange heat with the working fluid, which is circulated back to the catheter.