Implantable IMD Cell Membrane Permeability Monitoring via Beta-Dispersion Impedance
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Solution Overview
Problem
Existing methods for detecting intracellular edema and changes in cell membrane permeability require complex signal processing and multiple excitation/reference signals across different frequency ranges, posing high demands on equipment and processing power.
Innovation Solution
An implantable medical device generates a current/voltage signal within a frequency window extending from the β-dispersion frequency of cells to 90% of it, using two electrodes to apply and sense signals, allowing for simple impedance parameter calculation and monitoring of cell membrane permeability changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If complex signal processing involving cross-correlation products and multiple frequency ranges is used, then measurement precision for detecting intracellular edema is improved, but device complexity and processing requirements increase
Solution Approach 1:
The patent extracts and focuses on a specific frequency range (beta-dispersion frequency region) that is most sensitive to cell membrane permeability changes. By isolating this critical frequency band and using a single excitation frequency within this range, the complex multi-frequency cross-correlation processing is simplified to basic impedance measurement at one frequency, dramatically reducing computational requirements while maintaining detection precision for intracellular edema
Solution Approach 2:
The patent changes the measurement parameter from multi-frequency cross-correlation analysis to single-frequency impedance measurement in the beta-dispersion region. This parameter change exploits the fact that cell membrane permeability changes (during ischemia and edema formation) cause characteristic impedance changes at beta-dispersion frequencies, allowing accurate detection without complex signal processing
2Measurement precision
If multiple excitation/reference signals in different frequency ranges are used, then measurement precision is improved, but use of energy and processing power increases
Solution Approach 1:
The patent extracts the essential information needed for edema detection from a specific frequency band (beta-dispersion region). By using only a single excitation frequency within this band rather than multiple frequencies across different ranges, the energy required for signal generation and processing is significantly reduced while still capturing the permeability changes of cell membranes that occur during ischemia
Solution Approach 2:
The patent employs a simple, low-cost single-frequency excitation approach instead of expensive, power-intensive multi-frequency signal generation systems. The single-frequency impedance measurement in the beta-dispersion region provides sufficient information for edema detection with minimal energy consumption, making the device more suitable for implantable applications with limited power resources
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 early detection of ischemia and intracellular edema with reduced processing and power requirements, using traditional medical device units without the need for special sensors, and provides a straightforward monitoring method.
Implementation Method 1
a frequency window extending from the β-dispersion frequency of cells in a monitored tissue to about 90% of the β-dispersion frequency
Data Source
AI summary
An implantable medical device comprises a signal generator for generating a current signal having a frequency in a frequency window slightly less than the β-dispersion frequency of a tissue and applying the signal over the tissue. A signal measurer measures the resulting voltage signal and an impedance parameter is calculated from the applied and measured signal by a parameter determiner. A status monitor monitors the permeability status of cell membranes in the tissue based on this impedance parameter.