Superelastic Needle Tip Geometry to Reduce Coring and Tissue Trauma
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Solution Overview
Problem
Existing needles used in percutaneous medical procedures suffer from coring, which leads to undesirable tissue trauma, contamination, and foreign body response, particularly when made from superelastic alloys like nitinol, and conventional needles cause additional pain and tissue trauma due to size differences and kinking issues.
Innovation Solution
A needle design with a distal end featuring a non-cutting heel extending orthogonally to the central axis, combined with a deformable portion that deflects elastically to minimize lateral forces and ensure controlled insertion, using a superelastic material like nitinol to maintain flexibility and prevent kinking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a conventional needle with a cutting heel is used, then insertion forces are minimized through effective cutting, but coring occurs causing tissue trauma, contamination, and foreign body response
Solution Approach 1:
The harmful cutting function is extracted from the heel region by creating a non-cutting heel through orthogonal extension, while the cutting function remains concentrated at the point and cutting edge regions, thereby eliminating coring while preserving effective cutting capability
Solution Approach 2:
Different regions of the needle tip are given different functional qualities: the point and cutting edge maintain sharp cutting properties, while the heel is modified with orthogonal extension to provide a non-cutting, tissue-spreading function, allowing each region to perform its specific role optimally
2Object-affected harmful factors
If sandblasting is applied to dull the heel to prevent coring, then non-coring performance is achieved, but manufacturing complexity increases and flexibility is reduced
Solution Approach 1:
The mechanical post-processing method (sandblasting) is replaced with a geometric design solution (orthogonal heel extension), achieving the same non-coring function through shape rather than surface treatment, thereby simplifying manufacturing while maintaining flexibility
Solution Approach 2:
The heel geometry parameter is changed from a conventional angled bevel to an orthogonal extension, fundamentally altering the heel's interaction with tissue from cutting to spreading, thereby preventing coring without requiring additional manufacturing steps
3Manufacturing precision
If a rigid needle is used for insertion, then insertion precision is improved, but tissue trauma increases due to size differences and kinking of soft cannulas
Solution Approach 1:
The needle incorporates a flexible structure that can deflect during insertion, allowing the needle to navigate tissue more gently while maintaining insertion precision, thereby reducing tissue trauma associated with rigid needles
Solution Approach 2:
The needle transitions from a static rigid structure to a dynamic flexible structure that can adapt its shape during insertion, enabling controlled deflection to minimize tissue disruption while maintaining accurate placement
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 reduces tissue trauma, minimizes coring, and ensures reliable fluid flow through the needle lumen, providing a secure and efficient insertion method that is less painful and less prone to kinking.
Implementation Method 1
using a superelastic material like nitinol to maintain flexibility and prevent kinking
Implementation Method 2
a deformable portion that deflects elastically to minimize lateral forces and ensure controlled insertion
Data Source
AI summary
There is provided a needle comprising a needle tube extending along a central axis between proximal and distal ends of the needle, the needle tube defining a lumen, and the distal end defining an opening into the lumen. The needle comprises a point, a cutting edge, and a heel extending between inner and outer surfaces of the needle tube. At least a region of the heel extends substantially orthogonally to the central axis to provide a non-cutting edge of the distal end.