Electrode Impedance Sensing for Tissue Penetration Depth
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Solution Overview
Problem
Existing medical devices, such as cardiac pacemakers, face challenges in accurately assessing the penetration depth of electrodes in organic tissue, leading to potential dislocation and increased stimulus thresholds, without suitable indicators for complete insertion or withdrawal.
Innovation Solution
A system and method using two or more electrodes, including a screw electrode and a ring electrode, to apply measurement signals and analyze impedance changes, characterized by amplitude and phase, to determine the organic medium surrounding the electrode, allowing precise placement and preventing dislocation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If impedance measurements are used to assess electrode penetration depth, then information about electrode positioning can be obtained, but the measurement precision is insufficient to determine complete insertion or withdrawal
Solution Approach 1:
The patent applies parameter changes by utilizing multiple measurement frequencies (e.g., 50 Hz, 500 Hz, 5 kHz, 50 kHz) to characterize impedance at different frequencies. This multi-frequency approach transforms a single-parameter measurement into a multi-dimensional characterization, enabling detection of complete electrode insertion or withdrawal by identifying specific impedance patterns that indicate full penetration through tissue boundaries
Solution Approach 2:
The patent introduces another dimension by analyzing both magnitude and phase of impedance, and by examining impedance across multiple frequencies. This transforms a one-dimensional measurement (single frequency magnitude) into a multi-dimensional assessment, providing sufficient information to determine complete insertion or withdrawal states that were previously indistinguishable
2Reliability
If electrodes are inserted deeply into tissue for deep septal stimulation, then better stimulation capability is achieved, but the risk of tissue puncture and patient harm increases
Solution Approach 1:
The patent implements feedback by continuously monitoring impedance characteristics during electrode insertion and using multi-frequency measurements to provide real-time information about penetration depth. The system compares measured impedance patterns against known signatures of complete insertion, providing feedback to the operator to stop insertion at the appropriate depth and prevent over-penetration or tissue puncture
Solution Approach 2:
The patent applies preliminary action by performing multi-frequency impedance measurements before final electrode placement is confirmed. This allows the system to predict and prevent potential tissue puncture by identifying impedance patterns that indicate approaching critical depth, enabling preventive adjustment of insertion depth before harmful effects occur
3Loss of information
If traditional sensing and stimulus threshold methods are used to visualize electrodes, then electrode placement can be monitored, but penetration depth assessment remains impossible
Solution Approach 1:
The patent applies universality by using the same electrode structure for both traditional functions (sensing and stimulation) and the new function of penetration depth assessment. The multi-frequency impedance measurement capability is integrated into the existing electrode system, allowing a single device to perform multiple functions including visual feedback, penetration depth measurement, and stimulation without requiring separate specialized instruments
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 precise electrode placement in organic tissue, reducing power consumption and patient harm by providing accurate positioning and preventing tissue puncture.
Implementation Method 1
the analysis unit is further configured to determine an impedance between the two or more electrodes based on the measurement signal and characterize the organic medium surrounding the at least one electrode based on an amplitude and/or phase of the impedance
Implementation Method 2
the analysis unit is configured to apply a current pulse to at least one (first) electrode and wherein the analysis unit is further configured to characterize the organic medium surrounding the at least one electrode based on the morphology of the applied current pulse
Data Source
AI summary
A system for characterization of an organic medium surrounding an electrode, comprising: two or more electrodes, wherein at least one electrode of the two or more electrodes is configured to be insertable in tissue; and an analysis unit connectable to the two or more electrodes and configured to apply a measurement signal to the two or more electrodes, wherein the analysis unit is further configured to determine an impedance between the two or more electrodes based on the measurement signal and characterize the organic medium surrounding the at least one electrode based on an amplitude and/or phase of the impedance or real part and/or imaginary part of the impedance.