Shape-Memory Polymer Implant Programming via Compression Fixture
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Solution Overview
Problem
Mass-produced medical device implants made from shape-memory materials often lack uniformity in their temporary shape programming, which can affect their ability to transition back to the permanent shape effectively.
Innovation Solution
A compression fixture is used to program shape-memory polymer medical device implants by heating and compressing them to deform the material without fracturing, then cooling to set the temporary shape, ensuring consistent transformation from the temporary to the permanent state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If shape-memory materials are used to reduce implant size for smaller surgical entry sites, then invasiveness is reduced and recovery time is shortened, but manufacturing uniformity of the temporary shape is compromised
Solution Approach 1:
The patent applies parameter changes by controlling temperature and compression force during the programming process. The implant is heated to a transformation temperature above the glass transition temperature of the shape-memory polymer, which changes the material's properties to allow deformation. Specific compression forces are applied at specific temperatures to achieve uniform temporary shaping, resolving the contradiction between size reduction and manufacturing precision.
Solution Approach 2:
The patent utilizes phase transitions of the shape-memory polymer material. The material transitions from a rigid state at room temperature to a softened, deformable state when heated above its glass transition temperature. This phase transition enables uniform temporary shaping during programming while maintaining the ability to return to the permanent shape, thus achieving both size reduction and manufacturing uniformity.
2Ease of operation
If the implant is compressed into a temporary shape for implantation, then the surgical procedure becomes less invasive, but the uniformity of the temporary shape across mass-produced devices deteriorates
Solution Approach 1:
The patent applies preliminary action by pre-programming the implant with a specific temporary shape before sterilization and packaging. The compression fixture is designed to apply uniform compressive forces during the programming stage, ensuring that all implants receive identical treatment. This preliminary uniform deformation establishes consistent temporary shapes across mass-produced devices, which can then be uniformly deployed during surgery.
Solution Approach 2:
The patent replaces manual or inconsistent mechanical shaping with a controlled thermal-mechanical system. A compression fixture applies mechanical compression while the implant is held at a controlled temperature above its glass transition temperature. This substitution of pure mechanical deformation with thermally-assisted mechanical deformation ensures uniform temporary shaping across all implants, resolving the inconsistency problem.
3Shape
If compression force is applied to deform the shape-memory polymer, then the temporary shape is achieved, but material fracturing may occur
Solution Approach 1:
The patent changes the temperature parameter to resolve the contradiction between shape deformation and material integrity. By heating the shape-memory polymer above its glass transition temperature, the material transitions to a softer, more ductile state that can withstand compression forces without fracturing. Once compressed into the temporary shape, cooling the material restores its strength and structural integrity, allowing safe handling and implantation.
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 method ensures consistently uniform products that can effectively transition from the temporary to the permanent shape, facilitating smaller surgical entry sites and shorter recovery times in medical procedures.
Implementation Method 1
The compression fixture is then heated to a predetermined temperature for a predetermined period of time such that the polymeric material can be deformed without fracturing
Implementation Method 2
The compression fixture is then cooled, whereupon the cover and base are separated from each other
Implementation Method 3
Shape-memory materials have the ability to change from a permanent or desired shape into a temporary transitional shape and then back into the permanent or desired shape
Data Source
AI summary
A medical device implant made with a shape-memory material is originally produced in a “permanent” configuration. The implant is then “programmed” into a temporary (typically smaller sized) configuration to facilitate implantation, after which, an external stimulus activates the implant to return to its permanent configuration. Apparatus and methods include inserting a first portion of the implant into an aperture of a compression fixture base, heating the implant, and then driving and compressing the remaining portion of the implant, which has a different, typically larger profile than that of the first portion, into the aperture with a compression fixture cover to “program” the remaining portion. The resulting programmed implant has first and remaining portions that have identical, or substantially identical, profiles.