Contact Force Spring Mechanical Stops for Catheter Force Sensing
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Solution Overview
Problem
Catheter springs used in medical procedures, particularly those with balloon assemblies, are prone to irreversible deformation due to high tensile forces, leading to potential damage and loss of functionality.
Innovation Solution
Incorporating helical cuts with longitudinal deviations in the spring design to create mechanical stops that prevent overbending and overstretching, allowing simultaneous engagement of multiple stops to distribute force evenly and prevent sequential failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the spring is made more flexible to accommodate high tensile forces, then the spring can better withstand stress, but it becomes prone to irreversible deformation
Solution Approach 1:
The spring is divided into multiple segments by introducing helical cuts with longitudinal deviations, creating discrete mechanical stops at each cut. This segmentation allows the spring to flexibly withstand tensile forces while the stops prevent excessive deformation that would cause irreversible damage.
Solution Approach 2:
Mechanical stops are pre-positioned along the spring at locations that will engage before irreversible deformation can occur. These stops act in advance to limit the spring's travel and prevent damage, allowing the spring to operate safely within its elastic range even under high stress conditions.
2Reliability
If mechanical stops are added to prevent overbending and overstretching, then the spring's reliability improves, but the device complexity increases
Solution Approach 1:
The mechanical stops are merged with the spring structure itself by forming them as integral features of the helical cuts in the spring tube. This integration eliminates the need for separate stop components, reducing overall device complexity while maintaining the reliability benefits of having mechanical stops to prevent overbending and overstretching.
Solution Approach 2:
The spring design incorporates controlled geometric parameter changes through the helical cuts with longitudinal deviations. By carefully designing the position, depth, and spacing of these cuts, the mechanical stops provide necessary protection against irreversible deformation while maintaining a relatively simple overall spring structure that does not significantly increase device complexity.
3Strength
If multiple helical cuts are introduced to create mechanical stops, then the force distribution improves, but the manufacturing precision requirements increase
Solution Approach 1:
The spring is segmented into multiple sections by helical cuts, with each cut creating a mechanical stop. This segmentation distributes the force management across multiple stops rather than relying on a single stop, improving overall force distribution and preventing localized stress concentrations that could lead to failure.
Solution Approach 2:
The spring structure combines the continuous tube material with discrete helical cut features to create a composite structure. This composite design allows the spring to maintain the beneficial properties of the base material while incorporating mechanical stops that distribute forces evenly, achieving good force distribution without requiring extremely tight manufacturing tolerances on individual cut features.
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 mechanical stops effectively prevent irreversible deformation of the spring, ensuring consistent force measurement and functionality even under high stress conditions.
Implementation Method 1
a spring including a tube with at least one helical cut extending around a circumference of the tube, the at least one helical cut including deviations extending in a longitudinal direction of the tube
Implementation Method 2
respective ones of the mechanical stops are configured to engage simultaneously so that a force applied on the spring is shared among the respective mechanical stops
Data Source
AI summary
A catheter apparatus, including an elongated deflectable element, a distal assembly, a force sensor disposed between the elongated deflectable element and the distal assembly, and comprising a spring including a tube with at least one helical cut extending around a circumference of the tube, the at least one helical cut including deviations extending in a longitudinal direction of the tube, the deviations being configured to prevent overstretching and overbending of the spring.