Tissue Impedance Probe Boundary Detection
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Solution Overview
Problem
Existing tissue impedance measurement probes often produce false positive results when positioned over tissue boundaries, leading to inaccurate diagnoses due to impedance spectrum overlap between different tissue types.
Innovation Solution
A probe with a controller and processor that uses a balanced current path between diagonally opposite electrodes to determine if the probe is placed over homogeneous tissue, providing a visual or audio warning if a tissue boundary is detected, allowing for repositioning to avoid false positives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the probe is placed over a tissue boundary to expand measurement coverage, then the measurement area is increased, but false positive results occur due to impedance spectrum overlap between different tissue types
Solution Approach 1:
The probe divides the measurement function into two separate measurement modes: a first measurement mode for measuring impedance across the entire probe surface, and a second measurement mode for measuring impedance at specific regions between electrode pairs. This segmentation allows the system to detect tissue boundaries by comparing regional impedance variations while maintaining overall measurement coverage.
Solution Approach 2:
The system changes the measurement parameters by switching between different measurement modes. In the first mode, impedance is measured across all electrodes; in the second mode, impedance is measured between specific electrode pairs. By comparing parameter differences between these modes, the system identifies tissue boundaries and prevents false positives while maintaining expanded measurement coverage.
2Ease of manufacture
If the probe uses a simple four-electrode configuration for ease of manufacture, then manufacturing complexity is reduced, but the ability to detect tissue boundaries is insufficient
Solution Approach 1:
The four-electrode configuration serves multiple functions: it measures overall tissue impedance in the first measurement mode and detects tissue boundaries in the second measurement mode by measuring impedance between specific electrode pairs. This multi-functionality allows the simple structure to achieve both ease of manufacture and sufficient tissue boundary detection capability.
Solution Approach 2:
The probe dynamically switches between different measurement modes using the same four electrodes. The controller activates different electrode pairs for measurement based on the selected mode, allowing the static physical structure to perform dynamic measurement functions that improve tissue boundary detection without increasing manufacturing 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
The solution effectively reduces false positive results by accurately determining tissue homogeneity, ensuring reliable impedance measurements by alerting operators to reposition the probe, thereby improving diagnostic accuracy.
Implementation Method 1
measurements of tissue impedance in medical diagnosis applications
Implementation Method 2
An ac current I1 of 10 μA peak-to-peak is passed between two adjacent electrodes
Implementation Method 3
the real part of the resulting potential V1 between the two remaining electrodes is measured
Implementation Method 4
The ratio of the measured potential to the amplitude of the current determines the transfer impedance
Data Source
Figure 1~2
Figure 3~4
AI summary
A method for determining whether a probe for measuring the impedance of human or animal body tissue has been placed over a boundary between different tissue types is described. The probe used in the method comprises at least a first (16), a second (22), a third (18) and a fourth (20) electrode arranged such that the third (18) and fourth (20) electrodes are each located substantially the same distance from both the first (16) and second (22) electrodes. The method comprises: driving a current between the first (16) and the second (22) electrodes; measuring a first value of an electrical parameter between the third (18) and the fourth (20) electrode; and determining whether the probe has been placed over a boundary between different tissue types based on the first value. A probe for carrying out the method is also described.