Impedance Measuring Circuit for Tissue Therapy Patch Verification
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Solution Overview
Problem
In tissue therapy systems, particularly in irreversible electroporation and RF ablation, it is challenging to determine whether return patch electrodes are properly attached and if a reasonable impedance exists between the catheter and the patch, which can affect the efficacy and safety of the treatment.
Innovation Solution
A tissue therapy system with an impedance measuring circuit that drives currents between the catheter electrode and two return patch electrodes, using the catheter electrode as a reference voltage to detect voltages and measure impedances, ensuring proper attachment and impedance balance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If return patch electrodes are used in tissue therapy systems, then current return path is established for ablation therapy, but it becomes difficult to determine whether the patch is properly attached and whether reasonable impedance exists between catheter and patch
Solution Approach 1:
The system performs preliminary impedance measurements before delivering ablation therapy to verify proper patch attachment. The impedance measuring circuit measures impedance between the catheter electrode and each return patch electrode prior to therapy delivery, allowing the system to detect improper attachment or excessive impedance before treatment begins, thereby preventing unsafe operation
Solution Approach 2:
The system continuously monitors impedance between the catheter and return patches during the therapy procedure. This feedback mechanism allows real-time detection of changes in patch attachment quality or tissue impedance, enabling the system to alert the operator or adjust parameters to maintain safe and effective treatment conditions
2Reliability
If impedance measurement is implemented to ensure proper patch attachment, then safety and efficacy of therapy are improved, but system complexity increases due to additional measurement circuits
Solution Approach 1:
The impedance measuring circuit is integrated into the existing tissue therapy system and shares electrical connections with the ablation generator. The same electrodes used for therapy delivery are also used for impedance measurement, eliminating the need for separate measurement electrodes or additional physical connections. This multi-functional approach reduces overall system complexity while maintaining measurement capability
Solution Approach 2:
The system uses the existing electrical connection between the catheter and power supply as an intermediary pathway for impedance measurement. By injecting test signals through the same conductors used for therapy delivery and measuring the resulting voltages, the system avoids adding separate measurement wiring harnesses or connection points, thereby minimizing additional hardware complexity
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
Enables simultaneous measurement of impedances between catheter electrodes and return patches, determining proper attachment and ensuring safe and effective therapy delivery by preventing high current levels and ensuring consistent energy delivery.
Implementation Method 1
measure impedances between the catheter electrode and the return patches
Data Source
AI summary
Systems and methods for monitoring return patch impedances are provided. A tissue therapy system includes a catheter comprising at least one electrode, the catheter implantable in a patient, a first return patch electrode configured to be applied to skin of the patient, a second return patch electrode configured to be applied to the skin of the patient, and an impedance measuring circuit lectrically coupled to the at least one catheter electrode, the first return patch electrode, and the second return patch electrode. The impedance measuring circuit is configured to drive currents between the at least one catheter electrode, the first return patch electrode, and the second return patch electrode, detect, using a voltage at the at least one catheter electrode as a reference voltage, voltages generated in response to the driven currents, and measure impedances based on the driven currents and the detected voltages.