Five-Bevel Cannula Geometry to Reduce Penetration Force and Tissue Coring
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Solution Overview
Problem
Existing needles cause discomfort due to high penetration force and tissue coring during sample collection, necessitating an improved needle design that minimizes patient pain and prevents material lodgment in the lumen.
Innovation Solution
A multi-beveled needle point geometry with specific angles of inclination and rotation for the primary, middle, and tip bevels, reducing the force required for insertion and minimizing tissue coring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a conventional single-bevel needle tip is used, then the needle structure is simple, but the penetration force is high causing patient discomfort
Solution Approach 1:
The needle tip is segmented into multiple bevels (primary bevel, first middle bevel, second middle bevel, and tip bevels) with progressively varying angles. This segmentation allows each bevel to perform a specific function in the tissue penetration process, distributing the cutting action across multiple stages rather than concentrating force at a single point, thereby reducing overall penetration force and patient discomfort.
Solution Approach 2:
The invention changes the geometric parameters of the needle tip by implementing multiple bevels with different inclination angles (first angle, second angle, third angle where third > second > first) and different rotation angles. This parameter variation creates a progressive cutting action that reduces the peak penetration force compared to a conventional single-bevel design.
2Ease of manufacture
If a conventional needle tip geometry is used, then the manufacturing process is simple, but tissue coring occurs during penetration
Solution Approach 1:
The multi-bevel tip segments the tissue-cutting action into multiple sequential stages, with each bevel removing material at a different angle and position. This prevents the concentrated cutting action of a single bevel that causes coring, where tissue becomes lodged in the lumen. The segmented approach distributes the material removal across multiple controlled cuts.
Solution Approach 2:
The invention employs asymmetric bevel configurations with different inclination and rotation angles for each bevel. This asymmetry creates a progressive cutting pattern that prevents symmetric tissue compression and lodging that occurs with conventional symmetric single-bevel designs, thereby eliminating the coring effect.
3Ease of operation
If a multi-beveled needle tip with varying angles is used, then penetration force is reduced and patient comfort is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The multi-bevel angles and orientations are predetermined and pre-configured during needle manufacturing. The first middle bevel, second middle bevel, and tip bevels are pre-set with specific angle relationships (third angle > second angle > first angle) and rotation angles. This preliminary configuration ensures that during actual use, the progressive cutting action occurs automatically without requiring real-time adjustment, maintaining patient comfort while managing manufacturing precision through pre-established geometric relationships.
Data Source
AI summary
A needle including a cannula having a multi-beveled point is disclosed. The multi-beveled point includes a primary bevel, two middle bevels, and two tip bevels. Each of the middle bevels extends between the primary bevel and one of the tip bevels. The primary bevel is provided on the cannula at a first angle of inclination and a first angle of rotation, the two middle bevels are provided on the cannula at a second angle of inclination and a second angle of rotation, and the two tip bevels are provided on the cannula at a third angle of inclination and a third angle of rotation. The third angle of inclination is greater than the second angle of inclination, the second angle of inclination is greater than the first angle of inclination, and the second angle of rotation is equal to the third angle of rotation.