Inductive Sensor Spectrographic Analysis via Eddy Currents
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Solution Overview
Problem
Electrical impedance spectroscopy methods face challenges due to contact impedance issues with electrodes, corrosion, chemical reactions, and repulsion when analyzing biological tissues, which hinder accurate material analysis.
Innovation Solution
The use of multi-frequency inductive sensing to measure impedance through contactless eddy current sensing, avoiding electrodes by projecting a time-varying magnetic field into the target material to induce eddy currents and determine electromagnetic properties such as permittivity, permeability, and resistivity without direct contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electrodes are used for electrical impedance spectroscopy measurement, then measurement capability is achieved, but contact impedance issues, corrosion, chemical reactions, and tissue repulsion occur
Solution Approach 1:
The patent introduces an intermediary electromagnetic field as a mediator between the measurement system and the biological tissue. Instead of direct electrode-tissue contact, the system uses electromagnetic radiation to induce currents in the tissue, which are then detected. This intermediary approach eliminates harmful direct contact while maintaining measurement capability.
Solution Approach 2:
The patent replaces the mechanical contact-based measurement system (electrodes physically touching tissue) with an electromagnetic field-based system. The electromagnetic radiation induces currents in the tissue without physical contact, substituting mechanical interaction with field-based interaction to avoid contact-related problems.
2Reliability
If contactless inductive sensing is used, then contact-related issues are eliminated, but measurement precision may be reduced
Solution Approach 1:
The patent employs periodic electromagnetic radiation at multiple frequencies to probe the tissue properties. By using periodic excitation signals across a frequency spectrum, the system can extract detailed electromagnetic property information (permittivity, permeability, resistivity) at different penetration depths, maintaining measurement precision through frequency-domain analysis.
Solution Approach 2:
The patent changes the frequency parameter of the electromagnetic radiation to achieve different penetration depths and probe different tissue properties. By varying the frequency, the system can selectively measure electromagnetic properties at different depths, maintaining precision through multi-parameter measurement rather than single-point contact.
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
This approach provides non-invasive, accurate spectrographic material analysis by eliminating contact-related issues, allowing for precise determination of electromagnetic properties at various penetration depths, enhancing the reliability and safety of the analysis process.
Implementation Method 1
driving the inductive sensor with an excitation current at a sensor excitation frequency (ω); and thereby projecting a time-varying magnetic field into a sensing area on the surface of the target material, inducing eddy currents within the target material
Implementation Method 2
inducing eddy currents within the target material. The inductive sensor can be characterized by a sensor impedance Z(ω) that is a function of the sensor excitation frequency (ω), and the resulting eddy currents induced within the target material
Data Source
AI summary
A multi-frequency inductive sensing system can be used for spectrographic material analysis of a conductive target material (such as tissue) based on electrical impedance spectroscopy. An inductive senor can be driven with an excitation current at multiple sensor excitation frequencies (ω) to project a time-varying magnetic field into a sensing area on the surface of the target material, inducing eddy currents within the target material. The inductive sensor can be characterized by a sensor impedance Z(ω) as a function of the sensor excitation frequency (ω), and the resulting induced eddy currents. Multiple sensor impedance Zs(ω) measurements, at the multiple sensor excitation frequencies (ω), can be determined, which represent electromagnetic properties of the target material (such as permittivity ε, permeability μ, and resistivity ρ), based on the induced eddy currents. The multiple sensor excitation frequencies (ω), and corresponding multiple sensor impedance Zs(ω) measurements, can be selected for particular target penetration depths.