Ablation Cable Segmentation for Power and Fluid Ingress
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Solution Overview
Problem
Existing ablation cable assemblies face challenges in delivering high power electrosurgical energy efficiently while maintaining a predictable ablation zone and preventing fluid ingress, which affects the shape and size of the active zone around microwave antennas during tumor treatment.
Innovation Solution
The ablation cable assembly features a water-tight semi-rigid proximal portion, a flexible central portion with an exposed outer conductor, and a radiating portion that maximizes the thickness of the dielectric and inner conductor, allowing for continuous delivery of at least 150 watts of electrosurgical energy while minimizing fluid ingress and enhancing cooling through fluid impregnation of the conductive braid.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the size of the outer conductor is minimized to maximize energy delivery, then power delivery capability is improved, but fluid protection capability deteriorates
Solution Approach 1:
The cable assembly is divided into distinct segments: a proximal sealed portion with complete fluid protection, a transition zone, and a distal radiating portion with minimized outer conductor. This segmentation allows each section to be optimized for its specific function while maintaining overall system performance.
Solution Approach 2:
Different portions of the cable assembly have different structural characteristics. The proximal portion has a complete outer conductor for fluid protection, while the distal radiating portion has a minimized or absent outer conductor for maximum power delivery. This local differentiation resolves the contradiction by applying the appropriate structure in the appropriate location.
2Power
If the thickness of the dielectric and inner conductor is maximized for high power delivery, then power handling capability is improved, but cable diameter increases
Solution Approach 1:
The cable assembly separates the high-power radiating function (requiring thick dielectric and inner conductor) from the fluid protection function (requiring complete outer conductor coverage). This allows the radiating portion to be optimized for power handling without being constrained by fluid protection requirements.
Solution Approach 2:
The solution transitions from a uniform cross-sectional cable design to a variable cross-sectional design where the outer conductor thickness varies along the length of the cable. This dimensional change allows optimization of different parameters at different locations along the same cable assembly.
3Temperature
If the outer conductor is exposed to fluids for cooling, then cooling efficiency is improved, but fluid contact with inner conductor risk increases
Solution Approach 1:
The cable assembly is segmented into a proximal sealed portion that prevents fluid ingress and a distal radiating portion that allows fluid contact for cooling. The transition zone between these segments carefully manages the interface to maintain reliability while enabling cooling functionality.
Solution Approach 2:
The minimized outer conductor structure in the radiating portion acts as an intermediary that allows controlled fluid interaction for cooling while maintaining the integrity of the inner conductor and dielectric. The structural design of this intermediary element enables thermal management without compromising electrical protection.
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
This design enables efficient power handling and reduced attenuation, maintaining a predictable ablation zone and efficient cooling, even at small diameters, ensuring effective tumor treatment with minimized fluid contact with the inner conductor.
Implementation Method 1
The flexible central portion includes an exposed outer conductor that can be in contact fluids such as dielectric fluids, cooling fluids, or bodily fluids
Implementation Method 2
The flexible central portion includes an inner conductor, a dielectric disposed about the inner conductor, and a conductive braid disposed about the dielectric
Implementation Method 3
Electromagnetic fields can be used to heat and destroy tumor cells. These methods involve applying electromagnetic fields to heat or ablate tissue
Data Source
AI summary
A cable assembly includes a rigid portion, a flexible central portion, and a radiating portion. The rigid portion is configured to couple to a source of electrosurgical energy and to prevent fluid ingress towards the source of electrosurgical energy. The flexible central portion extends from the rigid portion and includes an inner conductor, a dielectric disposed about the inner conductor, and a conductive braid disposed about the dielectric. The radiating portion extends from the central portion and is configured to deliver electrosurgical energy to tissue.