Tumor Stimulation Electrodes With Four-Wire Impedance Sensing
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Solution Overview
Problem
Existing impedance measurement methods for biological tissues, such as cancerous tumors, suffer from interference due to voltage drops across electrodes and wires, leading to inaccurate impedance readings that hinder therapeutic guidance.
Innovation Solution
A four-wire impedance measurement system is employed, utilizing separate supply and sensing electrodes to isolate impedance measurements from interference within the medical device components, allowing for accurate impedance monitoring of cancerous tumors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a two-wire impedance measurement system is used, then the device complexity is reduced, but the measurement precision deteriorates due to voltage drops across electrodes and wires interfering with the readings
Solution Approach 1:
The measurement system is segmented into separate current delivery and voltage sensing functions. Four-wire leads divide the measurement circuit into independent current paths and voltage detection paths, allowing impedance measurement without interference from lead and electrode resistance.
Solution Approach 2:
The patent introduces an intermediary measurement approach where voltage is sensed separately from current delivery. The four-wire system acts as an intermediary mechanism that isolates the voltage measurement from the current-carrying paths, eliminating the direct interference that plagues two-wire systems.
2Measurement precision
If separate supply and sensing electrodes are used, then the impedance measurement precision is improved, but the device complexity increases due to additional wires and electrodes
Solution Approach 1:
The four-wire leads serve multiple functions: they deliver current through the tumor, sense voltage across the tumor, and provide isolation from electrode impedance. This multi-functionality justifies the increased complexity by delivering superior measurement accuracy and therapeutic monitoring capability.
Solution Approach 2:
The separate sensing electrodes provide continuous feedback on tumor impedance during treatment. This feedback mechanism enables real-time monitoring of therapeutic efficacy and allows for dynamic adjustment of treatment parameters, which outweighs the additional device complexity.
3Productivity
If impedance measurements are taken during electric field delivery, then therapeutic monitoring is enabled, but the measurement accuracy deteriorates due to interference from device component impedance
Solution Approach 1:
The system segments the electrical circuit into independent current delivery and voltage sensing pathways. This segmentation allows simultaneous therapeutic electric field delivery and accurate impedance measurement, as the measurement circuit does not share components with the therapy circuit, eliminating interference.
Solution Approach 2:
The four-wire sensing system acts as an intermediary that measures tumor impedance without being affected by the therapy electrode impedance. The separate sensing leads provide a measurement pathway that is electrically isolated from the current-carrying therapy leads, enabling accurate monitoring during treatment.
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 four-wire system provides precise impedance measurements independent of device component interference, enabling effective therapeutic monitoring and adjustment based on tissue impedance changes.
Implementation Method 1
The second electrode and the fourth electrode can form a sensing electrode pair configured to measure an impedance of the cancerous tumor independent of an impedance of the first electrode, the first wire, the third electrode, the third wire, and components in electrical communication therewith.
Implementation Method 2
The first electrode and the third electrode can form a supply electrode pair configured to deliver one or more electric fields at or near a site of the cancerous tumor.
Data Source
AI summary
Embodiments herein relate to a medical device for treating a cancerous tumor, the medical device having a first lead including a first wire and second wire; a second lead can include a third wire and fourth wire; and a first electrode in electrical communication with the first wire, a second electrode in electrical communication with the second wire, a third electrode in electrical communication with the third wire, and a fourth electrode in electrical communication with the fourth wire. The first and third electrodes form a supply electrode pair configured to deliver one or more electric fields to the cancerous tumor. The second and fourth electrodes form a sensing electrode pair configured to measure an impedance of the cancerous tumor independent of an impedance of the first electrode, the first wire, the third electrode, the third wire, and components in electrical communication therewith. Other embodiments are also included herein.