Microwave Ablation Probe Stepped Antenna Design

Solution Overview

Problem

Current microwave ablation probes face challenges with mechanical strength and efficiency due to weak coaxial cable construction, leading to potential mechanical breakdown and power attenuation, which complicates the treatment of varicose and spider veins.

Innovation Solution

A microwave ablation probe design featuring a radiating conductor with a matched stepped portion and dielectric material insulation, enhancing mechanical strength and impedance matching to improve power transfer and reduce heat generation, allowing for efficient energy delivery through a smaller, more flexible antenna.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If a quarter-wavelength antenna is used to maximize radiation efficiency, then the antenna length increases, but the device becomes less flexible and more prone to mechanical breakdown

Engineering Contradiction:

Improveradiation efficiencyVSAvoidmechanical strength

Core Design Contradiction:

PowerVSStrength

Solution Approach 1:

The patent changes the antenna length parameter from quarter-wavelength to substantially half-wavelength, which fundamentally alters the resonant frequency and radiation characteristics. This parameter change allows the antenna to achieve efficient radiation at shorter lengths, resolving the contradiction between radiation efficiency and mechanical strength by eliminating the need for long, fragile quarter-wavelength structures.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs composite construction by combining the antenna element with dielectric material insulation and protective coatings. The antenna is constructed as a composite structure with the conductive element surrounded by dielectric material, creating a mechanically stronger assembly that can withstand bending and mechanical stress while maintaining electrical performance.

Inventive Principle:

Principle #40Composite materials

2Strength

If the antenna is made shorter for flexibility, then mechanical strength improves, but radiation efficiency decreases

Engineering Contradiction:

Improvemechanical strengthVSAvoidradiation efficiency

Core Design Contradiction:

StrengthVSPower

Solution Approach 1:

The patent changes the antenna length parameter from quarter-wavelength to substantially half-wavelength, which fundamentally alters the resonant frequency and radiation characteristics. This parameter change allows the antenna to achieve efficient radiation at shorter lengths, resolving the contradiction between radiation efficiency and mechanical strength by eliminating the need for long, fragile quarter-wavelength structures.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent designs the antenna with flexible characteristics, allowing it to be dynamically positioned and shaped during procedures. The antenna element is constructed to be bendable and adaptable to curved venous paths, enabling the practitioner to optimize the antenna's position and orientation for maximum radiation efficiency while maintaining mechanical integrity through its flexible, shorter design.

Inventive Principle:

Principle #15Dynamics

3Reliability

If coaxial cable insulation is stripped off in the radiator portion, then electrical connection improves, but mechanical strength decreases and damage risk increases

Engineering Contradiction:

Improveelectrical connectionVSAvoidmechanical strength

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent extracts and removes the fragile insulation layer from the antenna portion of the coaxial cable, separating the electrical connection function from the mechanical protection function. The antenna element is constructed as a distinct component that interfaces with the coaxial cable's inner conductor, eliminating the need for insulation in the radiation portion while maintaining electrical connectivity through the coaxial interface.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent employs composite construction by combining the antenna element with dielectric material insulation and protective coatings. The antenna is constructed as a composite structure with the conductive element surrounded by dielectric material, creating a mechanically stronger assembly that can withstand bending and mechanical stress while maintaining electrical performance.

Inventive Principle:

Principle #40Composite materials

4Power

If a longer antenna is used for quarter-wavelength resonance, then radiation efficiency maximizes, but power attenuation increases and heat generation increases

Engineering Contradiction:

Improveradiation efficiencyVSAvoidpower attenuation

Core Design Contradiction:

PowerVSLoss of energy

Solution Approach 1:

The patent changes the antenna length parameter from quarter-wavelength to substantially half-wavelength, which fundamentally alters the resonant frequency and radiation characteristics. This parameter change allows the antenna to achieve efficient radiation at shorter lengths, resolving the contradiction between radiation efficiency and mechanical strength by eliminating the need for long, fragile quarter-wavelength structures.

Inventive Principle:

Principle #35Parameter changes

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 improved probe design increases mechanical strength, reduces power requirements, and achieves efficient energy transfer, enabling effective ablation with lower power input and flexibility for curved venous paths, minimizing complications like burns and bruising.

Implementation Method 1

a radiating conductor with matched stepped portion positioned in the cavity... configured to cover the radiating conductor... and provide insulation between the radiating conductor and the outer housing

Methodology Applied

Scientific EffectElectromagnetic radiation: Electromagnetic Induction

Implementation Method 2

a dielectric material placed in the cavity and configured to cover the radiating conductor with matched stepped portion and provide insulation between the radiating conductor and the outer housing

Methodology Applied

Scientific EffectDielectric insulation: Dielectric

Implementation Method 3

a microwave generator connector configured to connect to a microwave generator that generates an electromagnetic energy that is transmitted to the antenna by the feed coaxial cable

Methodology Applied

Scientific EffectMicrowave generation: Microwave Radiation

Implementation Method 4

Microwave ablation is a form of thermal ablation that uses electromagnetic waves in the microwave energy spectrum to locally heat the tissue and cause tissue necrosis

Methodology Applied

Scientific EffectDielectric heating: Dielectric Heating

Data Source

PatentUS11786303B2Microwave ablation probe

Publication Date: 2023.10.17 COSWAVE MEDICAL INC

AI summary

Examples of a probe for microwave ablation are disclosed. The probe comprises a feed coaxial cable and an antenna that has a cylindrical outer housing with a predetermined diameter and a predetermined length defining a cavity therein and a radiating conductor positioned within the cavity with a matching stepped portion. The antenna further comprises a dielectric material placed in the cavity between the radiating conductor and the outer housing of the antenna to increase the mechanical strength of the probe as well as to improve the power coupling to the tissue to be ablated. The design of the coaxial cavity of the antenna with radiating conductor with a stepped portion fitted into dielectric materials increases antenna's mechanical strength to withstand higher temperatures and reduces an energy reflected back to the feed coaxial cable due to a good impedance match between the antenna and the feed cable such that antennas with smaller length can be used to fit curved paths.