e-PTFE Membrane Thermoforming for Complex Hemocompatible Prostheses
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Solution Overview
Problem
Current haemocompatible objects made from expanded polytetrafluoroethylene (e-PTFE) are limited to simple shapes due to their high crystallinity and fiber orientation, which restricts their complex configuration possibilities.
Innovation Solution
A method involving an unstabilized e-PTFE membrane with non-preferentially oriented fibers is thermoformed by heating it above its freezing point and applying pressure, allowing it to be shaped into complex configurations, and then cooled and bonded to a prosthesis using an elastomer for a haemocompatible coating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If e-PTFE with high crystallinity and fiber orientation is used, then hemocompatibility is improved, but shape complexity is limited
Solution Approach 1:
The patent changes the thermal parameters of e-PTFE by using unstabilized material and heating it above its freezing point during forming, allowing the material to become more formable while maintaining hemocompatibility. This parameter change enables complex shapes to be achieved without sacrificing the material's biological compatibility.
Solution Approach 2:
The patent applies preliminary thermal treatment by heating the e-PTFE membrane above its freezing point before forming. This preliminary action softens the material, making it more pliable and capable of being formed into complex configurations, while the subsequent cooling stabilizes the new shape.
2Stability of the object's composition
If e-PTFE is thermally stabilized, then structural stability is improved, but formability is reduced
Solution Approach 1:
The patent introduces dynamic control of thermal properties by using unstabilized e-PTFE that can be temporarily softened above its freezing point during forming, then cooled to achieve the desired shape. The material transitions from a stable, difficult-to-form state to a more pliable state during processing, and back to stability after forming, enabling both formability and structural integrity.
3Shape
If heating temperature is increased above freezing point, then shape complexity is improved, but energy consumption increases
Solution Approach 1:
The patent exploits the phase transition of e-PTFE at its freezing point by heating it above this temperature during forming. This phase transition allows the material to become more pliable and formable, enabling complex shapes to be achieved. The energy input is concentrated at this critical transition point rather than requiring continuous high-energy processing.
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
Enables the production of haemocompatible objects with complex shapes, such as cardiac prostheses, maintaining chemical stability and porosity while ensuring compatibility with blood tissue.
Implementation Method 1
the membrane is heated, during its conformation to the configuration of said object, to a temperature above the freezing point of said expanded polytetrafluoroethylene
Implementation Method 2
pressing it against said forming mold by means of a pressure difference generated between the two faces of said membrane
Implementation Method 3
said membrane thus shaped is cooled while keeping it applied against said forming mold
Data Source
Figure 1~2
Figure 3
Figure 4~6
AI summary
- Method for producing a hemocompatible object of complex configuration and object thus obtained. - According to the invention, a membrane (1) of e-PTFE is thermoformed whose fibers (3) have no preferential orientation.