Tunable Helical Antenna for Microwave Ablation
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Solution Overview
Problem
Existing microwave ablation systems face challenges in maintaining precise temperature control and impedance matching during tissue ablation due to changes in tissue impedance during the procedure, which can lead to ineffective energy delivery and potential thermal damage to healthy cells.
Innovation Solution
A self-tuning, adjustable helical antenna element made from shape memory alloy (SMA) that dynamically changes dimensions in response to temperature or mechanical actuation, allowing for continuous and infinite adjustment of antenna tuning to maintain optimal energy delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed-dimension helical antenna is used, then the antenna structure is simple and easy to manufacture, but the antenna tuning cannot be adjusted to maintain optimal energy delivery when tissue impedance changes
Solution Approach 1:
The patent applies the dynamics principle by making the helical antenna element adjustable rather than fixed. The antenna can dynamically change its dimensions (such as the number of active turns or overall length) to adapt to changing tissue impedance conditions during ablation procedures, thereby maintaining optimal energy delivery without requiring a completely complex reconfigurable system.
Solution Approach 2:
The patent implements parameter changes by allowing physical modification of the antenna's dimensional parameters (length, number of turns, spacing) to tune its electrical characteristics. This enables the antenna to adapt to varying tissue impedance by changing its geometric parameters, achieving adaptability through straightforward structural modification rather than complex electronic control systems.
2Productivity
If microwave energy is delivered at high power to achieve effective ablation, then the ablation effectiveness is improved, but thermal damage to healthy cells increases due to unpredictable temperature control
Solution Approach 1:
The patent applies feedback by using temperature sensors positioned near the antenna tip to continuously monitor tissue temperature during ablation. This temperature information feeds back to the control system, which automatically adjusts the microwave power delivery to maintain temperatures within the therapeutic window (41.5°C to 45°C), ensuring effective ablation while preventing damage to healthy surrounding tissues.
Solution Approach 2:
The patent implements dynamics by enabling real-time adjustment of microwave power delivery based on actual tissue conditions. The system dynamically modulates the energy transmission to match the thermal response of the tissue, allowing high power delivery when needed for effective ablation while immediately reducing power when temperature thresholds are approached, thus controlling thermal damage.
3Ease of manufacture
If the antenna dimensions are fixed during manufacturing, then the manufacturing process is simple and fast, but the antenna cannot be tuned to compensate for tissue impedance changes during ablation
Solution Approach 1:
The patent applies dynamics by incorporating an adjustable mechanism into the antenna structure that allows post-manufacturing modification of antenna dimensions. The antenna can be mechanically extended or reconfigured during the procedure to tune its electrical length and impedance characteristics, combining relatively simple manufacturing with operational adaptability.
Solution Approach 2:
The patent implements segmentation by dividing the helical antenna into multiple discrete sections or turns that can be independently activated or deactivated. This segmentation allows the antenna to be manufactured in a compact, simple form while enabling selective engagement of different segments to achieve the desired electrical length and impedance matching during the procedure.
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 SMA-based helical antenna ensures predictable temperature control and effective energy distribution, minimizing thermal damage to healthy tissues while ensuring adequate ablation of targeted tissue, thereby improving the precision and safety of microwave ablation procedures.
Implementation Method 1
The helical antenna element may be formed from a shape memory alloy (SMA) material and configured to change one or more dimensions thereof in response to a change in temperature
Implementation Method 2
microwave energy generally radiates perpendicularly away from the axis of the conductor
Implementation Method 3
a high radio frequency electrical current in the range of about 500 MHz to about 10 GHz is applied to a targeted tissue site to create an ablation volume
Data Source
AI summary
An electromagnetic surgical ablation probe having a tunable helical antenna element includes a coaxial feedline having an inner conductor coaxially disposed within a dielectric, and an outer conductor coaxially disposed around the dielectric. The inner conductor and dielectric extend distally beyond a distal end of the outer conductor. A helical antenna element is operably coupled to a distal end of the inner conductor. During use, the antenna may be tuned by changing at least one dimension of the helical antenna element. Embodiments are presented wherein a dimension of the helical antenna element is changed by state change of a shape memory alloy, by a change in temperature, by activation of a piston by fluidic pressure, by linear motion of a conical tip, and by a manual screw-type adjustment.