Medical Probe Common Conductor for RF Leakage Cancellation
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Solution Overview
Problem
Medical catheters face a practical limit in diameter due to the need for multiple elements like ablation electrodes, strain gauges, and temperature sensors, which requires a large number of conductors, limiting their efficiency and flexibility.
Innovation Solution
A medical probe design that uses a common conductor for both high-intensity RF energy and thermocouple signals, employing a mixer to cancel RF leakage and modulate low-frequency signals onto an RF carrier for accurate temperature detection, reducing the number of conductors needed and enhancing detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple separate conductors are used for ablation electrode and thermocouple, then signal isolation and detection accuracy are improved, but catheter diameter increases
Solution Approach 1:
The patent combines the ablation electrode conductor and thermocouple conductors into a single common conductor. This merging allows both functions to share the same conductive path, eliminating the need for separate conductors and reducing catheter diameter while maintaining temperature detection capability through the thermocouple effect at the junction point
2Length of stationary object
If common conductor is used for ablation and thermocouple, then catheter diameter is reduced, but RF leakage interferes with temperature signal detection
Solution Approach 1:
The patent extracts the temperature signal from the common conductor by using a mixer that separates the low-frequency thermocouple voltage signal from the high-frequency RF leakage. The mixer downconverts the RF signal to a lower frequency where it can be filtered and detected, effectively removing the RF interference while preserving the temperature measurement
Solution Approach 2:
The patent introduces a mixer as an intermediary device between the common conductor and the temperature measurement circuit. The mixer acts as a signal conditioner that converts the RF-coupled thermocouple signal into a form that can be easily filtered and measured, blocking the harmful RF leakage from reaching the measurement circuit
3Reliability
If multiple separate conductors are used, then signal isolation is improved, but device complexity and conductor count increase
Solution Approach 1:
The patent makes the common conductor serve multiple functions: it acts as both the ablation electrode conductor for RF energy delivery and the thermocouple conductor for temperature sensing. This multi-functionality eliminates the need for separate conductors, reducing overall device complexity while maintaining signal isolation through the mixer-based separation system
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 approach reduces the catheter diameter, increases flexibility, and improves signal detection accuracy by minimizing the need for filtering and reducing conductor count, thereby enhancing the overall efficiency of the medical probe.
Implementation Method 1
The thermocouple is formed from two dissimilar conductors which are connected at a junction, and the thermocouple outputs a low level low-frequency voltage, of the order of tens or hundreds of millivolts, which is proportional to the temperature of the distal end
Implementation Method 2
A mixer is coupled to the non-common thermocouple conductor, thus receiving the thermocouple low level voltage with the RF leakage component. To recover the low level voltage, the mixer receives a portion of RF energy from the RF generator, and uses this for local oscillation
Implementation Method 3
The ablation electrode requires high intensity radiofrequency (RF) energy, typically on the order of a hundred volts or more, in order to operate
Data Source
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AI summary
A medical probe, including an ablation electrode and a first conductor connected to the ablation electrode. The first conductor is configured to convey ablation energy to the ablation electrode. The probe also includes a second conductor which is connected at a junction to the first conductor so as to form a thermocouple at the junction.