Helical Spring Electrode Ablation Probe Design
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Solution Overview
Problem
Existing ablation instruments face challenges in achieving both flexibility and mechanical stability, particularly when navigating through small bronchial tubes to treat lung tissue, requiring a balance between small diameter, high flexibility, and sufficient stiffness to pierce tissue while withstanding tensile forces and pressure.
Innovation Solution
A flexible ablation probe with helical spring electrodes and a design that allows for electrical connections without projecting beyond the instrument's outer contour, featuring a flexible hose arrangement with an inner hose and coating, and an insulating body that facilitates insertion and reduces bending resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the ablation instrument is made with a very small diameter to navigate through small bronchial tubes, then flexibility and ability to reach lung parenchyma is improved, but mechanical stability and ability to withstand tensile forces and pressure deteriorates
Solution Approach 1:
The ablation instrument is divided into multiple segments including a flexible hose arrangement with inner hose and coating, allowing the instrument to be both small in diameter and mechanically stable through modular construction that can flex and bend while maintaining structural integrity
Solution Approach 2:
The instrument combines different materials with complementary properties - the inner hose provides flexibility for navigation through small bronchial tubes, while the coating layer and electrode structure provide mechanical stability and electrical functionality, creating a composite structure that satisfies both small diameter and strength requirements
2Ease of operation
If the ablation instrument is made highly flexible with small bending radii to navigate bronchial tree, then ability to reach any area of lung parenchyma is improved, but stiffness required for piercing into tissue deteriorates
Solution Approach 1:
Different parts of the instrument have different mechanical properties - the hose arrangement and electrode structure are designed to be flexible for navigation, while the distal end and electrode tip maintain sufficient stiffness for tissue piercing, allowing the instrument to exhibit both flexibility and localized rigidity where needed
3Productivity
If electrodes are arranged on the flexible hose arrangement, then ablation functionality is improved, but flexibility of the instrument deteriorates due to stiff locations
Solution Approach 1:
The electrode is configured as a helical spring structure that can conform to the flexible hose arrangement, allowing the electrode to maintain its electrical functionality while flexing with the hose during navigation, eliminating stiff locations that would prevent bending
Solution Approach 2:
The helical spring configuration of the electrode introduces curvature and flexibility into the electrode structure itself, allowing it to bend and flex without creating rigid sections, thereby maintaining both ablation functionality and instrument flexibility
4Ease of manufacture
If electrical connection extension projects from the electrode, then electrical connection is simplified, but instrument outer contour is exceeded causing problems during bending
Solution Approach 1:
The electrical connection extension is positioned within the space defined by the helical spring electrode windings, nesting the connection structure within the electrode's own geometry, thereby simplifying electrical connection while maintaining a compact outer contour that does not project beyond the instrument
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 solution enables the ablation probe to maintain flexibility and mechanical stability, allowing for precise insertion and treatment of tissue with small bending radii and high angles, while ensuring no parts of the instrument project beyond its outer contour, enhancing its ability to reach and treat tumors effectively.
Implementation Method 1
At the distal end of the probe one or more electrodes are provided that are supplied with high frequency alternating current. The latter creates a thermal necrosis in the tissue.
Implementation Method 2
EP 2 309 941 B1 and EP 3 769 706 A1 propose for this purpose to provide the distal end of an ablation probe with an internal cooling.
Data Source
AI summary
An ablation instrument includes one or more electrodes that are configured as helical springs having ends for electrical connection that are configured as axial extensions. The electrodes are located on an inner hose serving as support, wherein the extensions are located at a smaller distance to the longitudinal axis than the windings of the electrode. Between the extension and the winding, a winding section is configured along which the distance toward the longitudinal center axis decreases from the radius of the winding to a lower value, so that the extension is located inward relative to the windings, i.e., closer to the center axis. For receipt of this extension and the associated electrical connection, the inner hose includes a trough.