Variable Stiffness NiTi Tissue Marker for Patient Comfort

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Solution Overview

Problem

Current lesion localization markers used in surgical procedures can cause discomfort and pain due to the risk of unintentional touching of the part extending from the body, and may be dislodged by external forces.

Innovation Solution

A rod-shaped marker with a super-elastic NiTi alloy, featuring a first part with high bending stiffness for secure anchoring in body tissue and a second part with significantly lower bending stiffness to minimize discomfort and prevent dislocation, made from nitinol tubes with different material properties achieved through heat or mechanical treatment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the marker extends from the body to guide surgeons, then the lesion location can be identified, but the patient experiences discomfort and pain from unintentional touching

Engineering Contradiction:

Improvelesion location identificationVSAvoiddiscomfort and pain

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The marker is designed with non-uniform bending stiffness along its length. The proximal portion (in body) has high bending stiffness for stable anchoring, while the distal portion (extending from body) has low bending stiffness to reduce discomfort from touching. This local differentiation of mechanical properties resolves the contradiction between reliable positioning and patient comfort.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The bending stiffness parameter of the marker is varied along its length rather than being uniform. By changing the stiffness parameter from high (proximal) to low (distal), the marker achieves both secure anchoring for reliable lesion identification and reduced harmful effects from patient contact with the external portion.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the marker is made rigid for secure anchoring, then the marker stays in place, but external forces can dislocate the marker

Engineering Contradiction:

Improvemarker stabilityVSAvoidresistance to dislocation

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The marker exhibits local quality in its mechanical properties: the proximal portion has high bending stiffness to maintain stable anchoring in body tissue, while the distal portion has low bending stiffness that allows it to flex and absorb external forces, preventing force transmission that could dislocate the marker.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The low-stiffness distal portion acts as a cushioning element that absorbs and dissipates external forces before they reach the anchored proximal portion. This beforehand cushioning prevents dislocation by reducing the impact of external forces on the critical anchoring region.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Reliability

If the marker has high bending stiffness throughout, then anchoring is secure, but the external portion transfers push forces to the anchored part

Engineering Contradiction:

Improveanchoring securityVSAvoidforce transfer to anchored part

Core Design Contradiction:

ReliabilityVSForce

Solution Approach 1:

The marker is designed with spatially varying bending stiffness: high in the proximal portion for secure anchoring, and low in the distal portion to minimize force transfer. This local differentiation ensures that the anchored portion remains stable while the external portion acts as a force-isolating flexible extension.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The low-stiffness distal portion serves as an intermediary element between the external environment and the anchored proximal portion. It mediates force transmission by absorbing and dissipating external pushes and blows, preventing these forces from reaching the critical anchoring region.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 marker significantly reduces the risk of discomfort and pain by being softer and less prone to dislocation, while maintaining effective guidance for surgeons during procedures.

Implementation Method 1

The marker is preferably made from a super-elastic NiTi alloy

Methodology Applied

Scientific EffectSuper-elasticity: Pseudoelasticity

Implementation Method 2

made from nitinol tubes with different material properties achieved through heat or mechanical treatment

Methodology Applied

Scientific EffectShape memory effect: Shape Memory Alloy

Data Source

PatentEP1948063B1Marker for marking an area in body tissue

Publication Date: 2010.08.18 WILLIAM COOK EURO

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AI summary

The invention relates to a marker for marking an area in body tissue, and a method for producing the marker. The marker is substantially rod-shaped with a first part having anchoring means intended to anchor the first part in body tissue in a body and a second part intended to substantially extend from the body while said first part is anchored in body tissue, and the marker comprises a super-elastic NiTi-alloy, and the bending stiffness of the first part is at least twice as high as the bending stiffness of the second part when the first part is anchored in body tissue.