Resilient Membrane and Compressible Piston Head for Dialysis Cassette
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Solution Overview
Problem
Conventional medical fluid cassettes in dialysis systems face challenges with membrane deformation and bulging due to increased fluid pressure, leading to inaccuracies in pumping volume and potential leakage.
Innovation Solution
A medical fluid cassette design featuring a resilient membrane that rebounds upon piston retraction, creating vacuum pressure and drawing fluid into the pump chamber without permanent deformation, and a piston head with a compressible circumferential region to evenly distribute pressure and prevent bulging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional membrane is used in the medical fluid cassette, then the structure is simple, but the membrane deforms and bulges under increased fluid pressure, leading to pumping volume inaccuracy and potential leakage
Solution Approach 1:
The patent employs a composite membrane structure consisting of an outer membrane layer and an inner support lattice. The outer membrane layer provides fluid containment while the inner support lattice prevents deformation and bulging under pressure. This composite construction resolves the contradiction by combining the flexibility needed for fluid containment with the structural rigidity required to maintain pumping volume accuracy and prevent leakage.
Solution Approach 2:
The patent uses a flexible membrane structure that incorporates a support lattice framework. The membrane itself remains flexible for fluid containment, while the embedded support lattice provides dimensional stability and prevents bulging. This approach allows the membrane to function as a flexible barrier while maintaining structural integrity under pressure, thereby preventing both deformation and leakage.
2Measurement precision
If a resilient membrane is used to rebound upon piston retraction, then vacuum pressure is created for accurate fluid drawing, but the membrane may deform under piston compression
Solution Approach 1:
The composite membrane structure with integrated support lattice allows the membrane to rebound elastically under piston compression while the lattice maintains its shape and prevents permanent deformation. The support lattice acts as a structural framework that preserves the membrane's resilience for vacuum generation while preventing the membrane from deforming during the compression phase, thus achieving both precise fluid drawing and shape stability.
3Shape
If a compressible piston head is used to evenly distribute pressure, then membrane bulging is prevented, but the device complexity increases
Solution Approach 1:
The piston head incorporates a compressible circumferential region that acts as a flexible element to evenly distribute pressure across the membrane surface. This flexible region prevents localized stress concentration and membrane bulging while maintaining a relatively simple overall piston head structure. The compressible region is integrated directly into the piston head, avoiding the need for complex external pressure distribution mechanisms.
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 design enhances pumping volume accuracy and prevents membrane bulging, ensuring reliable and precise fluid handling in dialysis systems by utilizing a resilient membrane and a compressible piston head to manage fluid pressure effectively.
Implementation Method 1
The second membrane is more resilient than the first membrane and is configured to rebound away from the base when a force used to press the second membrane toward the base is released
Implementation Method 2
expelling a medical fluid from a fluid pump chamber defined between a membrane and a recessed region of a base of a medical fluid cassette by using a piston to press the membrane into the recessed region
Implementation Method 3
drawing medical fluid into the fluid pump chamber by retracting the piston and allowing the membrane to rebound toward the retracting piston, wherein the membrane is allowed to rebound toward the retracting piston head due to resiliency of the membrane
Data Source
AI summary
This disclosure relates to medical fluid cassettes and related systems and methods. In certain aspects, a medical fluid cassette includes a base having a first region and a second region, a first membrane overlying the first region of the base, and a second membrane overlying the second region of the base. The second membrane is configured to rebound away from the base when a force used to press the second membrane toward the base is released.