Sensor Guide Wire Locking Member Joining Dissimilar Metals

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Solution Overview

Problem

Joining sections of a sensor guide wire made from different non-weld-compatible metals, such as stainless steel and Nitinol, is unreliable due to incompatibility, leading to insecure fastening of joints.

Innovation Solution

A sensor guide wire design featuring a tubular section with a through-going opening and a locking member that is inserted to secure the second elongate section, allowing for reliable joining using techniques like welding, soldering, or gluing, with the locking member made from a compatible material.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If sections of guide wire are made from different materials (stainless steel and Nitinol), then the guide wire can achieve desired mechanical properties and flexibility, but the joining of these sections becomes unreliable due to non-weld-compatible materials

Engineering Contradiction:

Improvematerial selection flexibilityVSAvoidjoining reliability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The guide wire is divided into multiple sections made from different materials (stainless steel and Nitinol), each section being independently manufactured with specific mechanical properties. The locking member creates a segmented assembly that allows material diversity while maintaining overall structural integrity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A locking member made from a material compatible with both stainless steel and Nitinol serves as an intermediary component. This locking member (which could be made from aluminum bronze, phosphor bronze, or other compatible alloys) enables reliable joining of the non-weld-compatible metal sections through mechanical interlocking rather than welding.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Strength

If traditional welding methods are used to join guide wire sections, then a secure connection can be achieved, but it is not feasible when joining non-weld-compatible metals like stainless steel and Nitinol

Engineering Contradiction:

Improvejoint strengthVSAvoidmanufacturing feasibility

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The welding process (thermal/chemical joining method) is replaced with a mechanical joining system using a locking member. The locking member features include a head portion and a body portion with a locking geometry that mechanically secures the guide wire sections together without requiring welding, soldering, or other thermal processes.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The joining method parameters are changed from thermal processes (welding temperature, heat input) to mechanical parameters (locking member geometry, insertion force, interference fit dimensions). This parameter change enables joining of materials that are incompatible with thermal processes.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If the guide wire uses a locking member for joining sections, then reliable assembly of different materials is achieved, but the device structure becomes more complex

Engineering Contradiction:

Improveassembly reliabilityVSAvoidstructural complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The locking member combines multiple functions into a single component: it serves as a connector, a mechanical fastener, and a material interface element. The head portion and body portion are integrated into one piece that simultaneously achieves section joining, material compatibility, and structural support.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The locking member design is made universal to work with different material combinations (stainless steel-Nitinol, stainless steel-stainless steel, etc.). The same basic locking member geometry can be used throughout the guide wire assembly, reducing the need for specialized joining components for each material interface.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS8579832B2Joining of sensor guide wire

Publication Date: 2013.11.12 ST JUDE MEDICAL COORDINATION CENT

AI summary

There is a sensor guide wire (1) for intravascular measurements of physiological variables in a living body. The sensor guide wire (1) comprises at least two elongate sections, a first tubular elongate section (2) being tubular in the longitudinal direction of the sensor guide wire (1), and a second elongate section (3) that is adapted to be inserted a predetermined distance (5) into said first tubular section (2), a sensor element (10) provided in the distal part of said sensor guide wire (1), for measuring the physiological variable and to generate a sensor signal in response to said variable, at least one signal transmitting cable connected to the sensor element (10) to transmit sensor signals to a male connector provided in the proximal part of said sensor guide wire (1). The tubular section (2) is provided with at least one through-going opening (4) in a direction perpendicular to the longitudinal direction of the guide wire (1) and positioned a second predetermined distance (6) from one end of the tubular section (2), wherein the guide wire (1) comprises a locking member (7) to be fitted into the opening (4) in order to join the sections (2, 3) together when the second elongate section (3) is inserted into the tubular section (2).