Hollow Cylindrical Electrode for Uniform RF Tissue Heating
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Solution Overview
Problem
High-frequency RF energy systems for heating biological tissue face limitations in electrode size due to the skin effect, resulting in uneven heat distribution and reduced penetration depth, making it challenging to achieve even heating over large areas without distortion of the electromagnetic field.
Innovation Solution
A system using a hollow cylindrical electrode with an annular surface exceeding 3 cm in diameter, allowing RF currents to flow in parallel along cylindrical surfaces, ensuring uniform current intensity and heat distribution across the contact area, and potentially employing concentric annular electrodes to increase treatment area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a large diameter electrode is used to treat large areas, then the treatment area is increased, but the skin effect causes uneven current distribution and electromagnetic field distortion
Solution Approach 1:
The electrode is segmented into multiple concentric annular sections, each independently controllable. This allows different regions of the electrode to operate at different phases or power levels, compensating for skin effect variations across the large contact area and achieving uniform heat distribution.
Solution Approach 2:
Different annular sections of the electrode are assigned different phases or power levels based on their specific heating requirements. The central region and peripheral regions can be controlled differently to account for variations in current distribution caused by the skin effect, achieving localized optimization of heating uniformity.
2Temperature
If high frequency RF energy is used to increase penetration depth, then dielectric heating is achieved, but the skin effect limits effective electrode size
Solution Approach 1:
The electrode surface is divided into multiple annular sections that can be independently controlled. This segmentation allows the system to effectively manage current distribution across large areas by adjusting the phase and power of each section, overcoming the skin effect limitation that would otherwise restrict electrode size at high frequencies.
Solution Approach 2:
The invention introduces a dimensional approach by using concentric annular sections with different radial positions. By controlling current flow in multiple concentric zones rather than a single flat surface, the system achieves uniform heating across large areas while maintaining effective penetration depth through dielectric heating mechanisms.
3Ease of manufacture
If a flat or spherical contact surface is used for simple electrode design, then manufacturing is easier, but heat distribution becomes uneven at the periphery
Solution Approach 1:
The electrode contact surface is segmented into multiple concentric annular sections, each capable of independent phase and power control. This segmentation allows compensation for the inherent uneven heat distribution at the periphery of large electrodes by applying different control parameters to different regions, achieving uniform overall heating while maintaining manufacturing simplicity.
Solution Approach 2:
Different annular sections of the electrode are assigned different phases or power levels based on their specific heating requirements. The central region and peripheral regions can be controlled differently to account for variations in current distribution caused by the skin effect, achieving localized optimization of heating uniformity.
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 effective dielectric heating over larger areas with uniform heat distribution, overcoming the skin effect limitations and achieving consistent heating across the biological tissue without electromagnetic field distortion.
Implementation Method 1
the heating is instead caused predominantly by dielectric heating, resulting from rotation of water dipoles in the alternating fields
Implementation Method 2
The skin effect is the tendency for high frequency current to flow near the surface of an electrical conductor rather than uniformly through its entire cross section
Data Source
AI summary
A system is disclosed for heating biological tissue via RF energy. The system comprises a source of RF energy at a frequency in excess of 25 Mhz and an applicator incorporating an electrode connected to the RF source for introducing RF energy into the biological tissue. The electrode comprises a hollow cylinder of which an end remote from the RF source defines an annular surface for contacting the biological tissue, the annular surface having an out diameter in excess of 3 cm.