Microwave Ablation Antenna Feedpoint Impedance Optimization

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Solution Overview

Problem

Microwave ablation procedures face challenges in achieving maximum energy transfer to the antenna due to impedance mismatch between the antenna and the feed line, leading to energy reflection and inefficient heating patterns, which can result in unwanted heating of healthy tissue.

Innovation Solution

An integrated matching network is incorporated into the feedpoint structure of the microwave dipole antenna, utilizing a combination of dielectric materials with varying permittivity constants and specific coaxial cable and hypotube dimensions to optimize the impedance matching, ensuring maximum energy transfer by adjusting the lengths and materials used in the proximal and distal radiating sections.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If a traditional dipole antenna structure is used with standard coaxial cable connection, then the device complexity is low, but impedance mismatch occurs causing energy reflection and inefficient heating

Engineering Contradiction:

Improveenergy transfer efficiencyVSAvoidantenna feedpoint structure

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The patent combines the matching network with the antenna feedpoint structure, integrating multiple functions (impedance matching and energy transfer) into a single unified component rather than using separate matching network and antenna elements

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent applies different dielectric materials with specific permittivity constants to different sections of the feedpoint structure (proximal section with first dielectric, distal section with second dielectric), optimizing impedance matching at each location rather than using uniform materials throughout

Inventive Principle:

Principle #3Local quality

2Loss of energy

If impedance matching is optimized using multiple dielectric materials and adjusted dimensions, then energy transfer efficiency improves, but the manufacturing precision requirements increase

Engineering Contradiction:

Improveenergy reflectionVSAvoidcoaxial cable and hypotube dimensions

Core Design Contradiction:

Loss of energyVSManufacturing precision

Solution Approach 1:

The patent optimizes specific geometric parameters (lengths of proximal and distal radiating sections, outer conductor diameter) and material properties (permittivity constants of dielectric materials) to achieve impedance matching, transforming a complex electromagnetic problem into a set of manageable dimensional and material parameter specifications

Inventive Principle:

Principle #35Parameter changes

3Object-affected harmful factors

If microwave energy is delivered with insufficient impedance matching, then the device operation is simple, but unwanted heating of healthy tissue occurs

Engineering Contradiction:

Improveheating of healthy tissueVSAvoidfeedpoint structure

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent introduces dielectric materials with specific permittivity constants as intermediary elements between the coaxial cable and the radiating sections, acting as impedance transformation mediators that gradually transition the impedance to match the antenna, thereby controlling energy distribution and preventing unwanted heating

Inventive Principle:

Principle #24Intermediary (Mediator)

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 integrated matching network enhances energy transfer efficiency, reducing energy losses and distortion, thereby improving temperature control and minimizing damage to healthy tissues during microwave ablation procedures.

Implementation Method 1

utilizing a combination of dielectric materials with varying permittivity constants and specific coaxial cable and hypotube dimensions to optimize the impedance matching

Methodology Applied

Scientific EffectImpedance matching: Dielectric Permittivity

Implementation Method 2

The antenna is operable to deliver energy to tissue and includes a proximal radiating section and a distal radiating section

Methodology Applied

Scientific EffectMicrowave radiation: Microwave Radiation

Implementation Method 3

These types of treatments, known generally as hyperthermia therapy, typically utilize electromagnetic radiation to heat diseased cells to temperatures above 41° C.

Methodology Applied

Scientific EffectDielectric heating: Dielectric Heating

Data Source

PatentUS8282632B2Feedpoint optimization for microwave ablation dipole antenna with integrated tip

Publication Date: 2012.10.09 COVIDIEN LP

AI summary

A microwave ablation system includes a generator operable to output energy and an antenna coupled to the generator via a coaxial cable. The antenna delivers energy to tissue and includes a proximal radiating section and a distal radiating section. The antenna also includes a feedpoint section defined by the portion of the distal radiating section that underlaps the proximal radiating section.