Fat Thickness Estimation Using Dual-Frequency Impedance Ratios

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Solution Overview

Problem

Inaccurate bioelectrical impedance measurements due to insufficient contact between electrodes and the body during fat thickness estimation, particularly in areas like the abdomen or upper arm, lead to unstable measurement accuracy.

Innovation Solution

A fat thickness estimating system that includes a storage unit for impedance ratio information, a measured impedance value acquiring unit, and an estimation unit to calculate fat thickness based on impedance values at different frequencies, along with a detection unit for contact state and a display unit to show contact results, ensuring stable and accurate measurements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If electrodes are pressed against the body to measure impedance for fat thickness estimation, then measurement capability is improved, but contact uniformity deteriorates leading to inaccurate impedance measurements

Engineering Contradiction:
Improvefat thickness measurement accuracyVSAvoidcontact state stability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent transforms the single-impedance measurement approach into a dual-frequency measurement approach. By measuring impedance at two different frequencies and calculating their ratio, the system changes the measurement parameters to eliminate the influence of contact state variations. This allows accurate fat thickness estimation even when electrode contact is uneven, as the ratio calculation cancels out the contact impedance component.

Inventive Principle:
Principle #35Parameter changes

2Ease of operation

If single frequency impedance measurement is used, then measurement simplicity is improved, but measurement accuracy deteriorates due to contact impedance influence

Engineering Contradiction:
Improvemeasurement simplicityVSAvoidimpedance measurement accuracy
Core Design Contradiction:
Ease of operationVSMeasurement precision

Solution Approach 1:

The system measures impedance at two different frequencies (first frequency and second frequency) and uses the ratio of these measurements. This parameter change from single-frequency to dual-frequency measurement enables the system to distinguish between contact impedance and tissue impedance, thereby improving measurement accuracy while maintaining operational simplicity through automated ratio calculation.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The impedance ratio serves as an intermediary parameter that mediates between the raw impedance measurements and the final fat thickness estimation. By introducing this intermediate calculation step, the system eliminates the direct influence of contact state on the final result, as the ratio operation cancels out the contact impedance component.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 system achieves stable and accurate fat thickness estimation by standardizing impedance measurements using ratios of bioelectrical impedance at different frequencies and detecting contact states, reducing the influence of uneven electrode contact on measurement accuracy.

Implementation Method 1

a method of estimating a fat thickness value by causing a current to flow into a living body, measuring impedance (bioelectrical impedance) in the living body

Methodology Applied
Scientific EffectBioelectrical impedance: Electrical Resistance

Data Source

PatentEP3114993B1Fat thickness estimation device, fat thickness estimation system, fat thickness estimation method, and program
Publication Date: 2022.07.06 THE KITASATO INSTITUTE
  • EP3114993B1 patent drawingFigure 1
  • EP3114993B1 patent drawingFigure 2
  • EP3114993B1 patent drawingFigure 3~5

AI summary

A fat thickness estimating device includes a storage unit (180) that stores information indicating relationship between fat thickness and ratio of bioelectrical impedance in a first condition and bioelectrical impedance in a second condition, a measured impedance value acquiring unit configured to acquire a measured impedance value in the first condition of a target living body and a measured impedance value in the second condition of the target living body, and an estimation unit (193) configured to calculate a fat thickness value in the target living body based on the information and a ratio of the measured impedance value in the first condition and the measured impedance value in the second condition.