Stent with Segmented Expansion Force for Accurate Placement
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Solution Overview
Problem
Current minimally invasive treatment techniques face challenges with stents that either fail to adequately expand body lumens due to insufficient expansion force or suffer from the 'jumping phenomenon' when released, leading to inaccurate placement and potential restenosis.
Innovation Solution
A tubular medical instrument with a specific alloy composition and structure, featuring distinct end and central portions with controlled expansion forces and phase transformation temperatures, allowing for precise ejection and placement, and a transfer device with an anti-jumping layer to prevent deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the tubular medical instrument is released from the lumen of the transfer device, then the stent expands to treat the affected area, but the expansion force causes the instrument to jump over the affected area
Solution Approach 1:
The tubular medical instrument is divided into multiple sections along its axial direction, with each section having different expansion force characteristics. The distal and proximal end portions have lower expansion forces while the central portion has higher expansion force, preventing the instrument from jumping while ensuring adequate expansion at the affected area.
Solution Approach 2:
Different portions of the tubular medical instrument are designed with locally optimized properties. The end portions have reduced expansion force to prevent jumping, while the central portion maintains high expansion force for effective treatment, creating a non-uniform distribution of mechanical properties along the instrument's length.
2Reliability
If the expansion force is increased to ensure adequate lumen expansion, then the treatment effectiveness improves, but the instrument cannot be placed accurately at the affected area
Solution Approach 1:
The instrument is segmented into zones with different expansion force levels. The central portion provides strong expansion force for reliable treatment, while the end portions provide lower expansion force for accurate placement, allowing both treatment effectiveness and placement accuracy to be achieved simultaneously.
3Ease of operation
If the tubular medical instrument is reduced in diameter for loading into the transfer device, then the minimally invasive capability is maintained, but the expansion force is insufficient to adequately expand the body lumen
Solution Approach 1:
The instrument employs local quality optimization where the central portion is designed with high expansion force capability to overcome the limitation of reduced overall diameter. This allows the compressed instrument to fit through small access points while the central section delivers sufficient expansion force for effective treatment.
4Device complexity
If the expansion force is distributed uniformly along the instrument, then the structure is simpler, but the end portions cannot sufficiently expand the body lumen while the central portion may cause jumping
Solution Approach 1:
Rather than uniform distribution, the invention applies local quality by creating a non-uniform expansion force distribution. The central portion has higher expansion force for adequate lumen expansion, while end portions have lower expansion force to prevent jumping, optimizing both reliability and placement stability.
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 solution enables accurate placement of stents by adjusting expansion forces and using a nickel-titanium alloy with controlled phase transformations, preventing restenosis and ensuring the stent remains in place without jumping or deforming.
Implementation Method 1
the alloy has a transformation start temperature As and a transformation finish temperature Af
Implementation Method 2
A tubular medical instrument made of an alloy includes one end portion, the other end portion, and a central portion
Data Source
AI summary
A tubular medical instrument which can be easily ejected from a transfer device and accurately placed in a case the tubular medical instrument is released from the transfer device and placed at an affected area is provided. A tubular medical instrument includes ends portions, and a central portion, wherein each of the end portions is a region including one axial end of the tubular medical instrument and having a length of 10% with respect to an axial length L1 of the tubular medical instrument, the central portion is a region including an axial center of the tubular medical instrument and having a length of 10% with respect to the axial length L1 of the tubular medical instrument, and a ratio (difference V/difference W) is 3 or more.