Impedance Transformer for Microwave Electrosurgical Energy Delivery
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing electrosurgical instruments that deliver microwave frequency energy into tissue face challenges in providing controlled, localized delivery, particularly in the gastrointestinal tract, due to impedance mismatch between the instrument and biological tissue, leading to inefficient energy transfer.
Innovation Solution
Incorporating an impedance transformer at the distal end of a coaxial transmission line, configured to match the impedance of the transmission line to the tissue, allowing for direct and efficient coupling of microwave energy into a localized area by adjusting the length and characteristic impedance of a further coaxial transmission line.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If an exposed end of a coaxial transmission line is pressed against tissue to deliver microwave energy locally, then localized energy delivery is achieved, but impedance mismatch causes significant energy reflection
Solution Approach 1:
A quarter-wave impedance transformer section is inserted between the coaxial transmission line and the tissue interface. This intermediary section has a characteristic impedance that is the geometric mean of the source and load impedances, and its length is one-quarter of the wavelength at the operating frequency. This transformer acts as an impedance matching bridge, converting the 50-ohm source impedance to match the lower tissue impedance, thereby minimizing reflections and maximizing power transfer efficiency.
Solution Approach 2:
The impedance transformer section changes the electrical parameters (characteristic impedance and electrical length) along the transmission path. By carefully selecting the characteristic impedance and length (quarter-wavelength) of the transformer section, the system transforms the impedance seen by the source to match the load, optimizing energy transfer. This parameter transformation occurs naturally through the distributed nature of the transmission line itself.
2Ease of operation
If existing electrosurgical instruments are used to deliver microwave energy, then general tissue treatment is possible, but controlled localized delivery is difficult to achieve
Solution Approach 1:
The instrument design provides localized energy delivery by using a coaxial transmission line with a controlled exposed end that contacts only a specific region of tissue. The electromagnetic energy is confined to the area surrounding the exposed end, creating a localized treatment zone. This allows precise targeting of specific tissue regions while leaving surrounding areas unaffected, achieving both ease of localized control and maintained energy efficiency through proper impedance matching.
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 configuration enables controlled and efficient delivery of microwave energy, reducing reflections and increasing the amount of energy transferred to the tissue, facilitating precise coagulation or ablation in localized areas.
Implementation Method 1
a first coaxial transmission line for conveying microwave frequency energy
Implementation Method 2
the second coaxial transmission line having a length and a characteristic impedance that are configured to better match the impedance of the first coaxial transmission line to the tissue
Implementation Method 3
couple microwave frequency electromagnetic energy directly to the tissue from an exposed end of a coaxial transmission line
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An electrosurgical instrument for delivering microwave energy having a predetermined frequency into biological tissue in contact with the instrument, wherein the instrument comprises a first coaxial transmission line having a second coaxial transmission line connected to the distal end thereof, the second coaxial transmission line having a length and a characteristic impedance that are configured to match the impedance of the first coaxial transmission line to the load impedance at the distal end of the distal coaxial transmission line when the instrument is in contact with the tissue, at the operating frequency.