Bonded Center Strut Catheter for Force Sensing
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Solution Overview
Problem
Existing medical catheters lack accurate force sensing and uniform deflection characteristics at the tip, which are crucial for procedures involving tissue ablation and dynamic tissue interaction, particularly in minimally invasive treatments within body spaces.
Innovation Solution
A catheter design featuring a bonded center strut with integrated strain gages for force and deflection measurement, combined with puller wires for bidirectional steerable tip deflection, creating a composite structure that maximizes internal volume and torsional rigidity while minimizing outer diameter, enabling precise force detection and uniform on-plane deflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a center strut is added to the catheter tip to improve torsional rigidity and deflection characteristics, then the structural stability is improved, but the outside diameter of the catheter tip increases
Solution Approach 1:
The center strut is positioned within the catheter tip structure, nested inside the outer catheter wall. This allows the strut to provide torsional rigidity and deflection control while being contained within the existing outer diameter envelope, minimizing the increase in overall catheter size.
Solution Approach 2:
The catheter tip employs a thin-walled flexible outer shell that accommodates the center strut. The flexible shell allows the strut to provide structural support while maintaining a compact outer diameter, and the thin-walled construction minimizes the space required for the overall structure.
2Measurement precision
If strain gages are affixed to the center strut for force sensing, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The center strut serves multiple functions: it provides torsional rigidity, enables bidirectional deflection control, and acts as a substrate for force sensing. By integrating strain gages onto the existing strut structure, the same component performs both mechanical support and measurement functions, reducing overall device complexity.
Solution Approach 2:
The center strut's structural deformation under load directly generates the measurement signal through the affixed strain gages. The strut's own mechanical response to applied forces is utilized for sensing, eliminating the need for separate sensing mechanisms and simplifying the overall device architecture.
3Volume of moving object
If the center strut is bonded along its entire length to maximize internal volume, then manufacturing precision is improved, but the ease of manufacture decreases
Solution Approach 1:
The center strut is bonded continuously along its entire length to the catheter tip structure. This continuous bonding maximizes the internal volume available for puller wires and other components, and ensures uniform structural integration throughout the strut's length, providing consistent mechanical performance.
Solution Approach 2:
The catheter tip employs a composite construction combining the center strut material with the catheter tip material through bonding. This composite structure integrates two different materials to achieve both the structural requirements of the strut and the flexibility requirements of the catheter tip, while the bonding creates an inseparable unified structure.
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 catheter provides accurate force sensing and enhanced deflection capabilities, ensuring precise tissue interaction and improved procedural outcomes by maintaining constant torque and deflection forces during tip curvature, addressing the limitations of prior art designs.
Implementation Method 1
On the bonded center strut one or more strain gage force sensors are affixed for measuring catheter tip deflection and tip axial and side forces
Implementation Method 2
maximizes the open internal volume of the catheter tip and the torsional rigidity of the catheter tip while minimizing the outside diameter of the catheter tip and providing uniform on-plane tip deflection
Data Source
AI summary
A force-sensing catheter for diagnosing or treating the vessels found within a body or body space includes a center strut that is bonded, preferably thermally, along its longitudinal axis with the thermoplastic tubular member within which it is housed. The tubular member preferably has three layers: an inner layer, a braided layer and an outer layer. One or more semiconductor or metallic foil strain gages are affixed to the center strut in order to provide a measure of the bending and torsional forces on the distal tip of the catheter. Temperature compensation is achieved by having a temperature sensor near the strain gages and calibrating the catheter over a range of temperatures.