Bioimpedance Parameter Estimation for Portable Devices
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Solution Overview
Problem
Existing impedance analysis techniques are computationally expensive and difficult to implement in real-time or portable devices with limited computational power, making it challenging to accurately determine biological parameters such as cardiac function and oedema using bioelectrical impedance measurements.
Innovation Solution
A method and apparatus that iteratively modify parameter value estimates by comparing theoretical impedance values to measured values, using linear regression and chord analysis to determine modification directions, allowing for efficient determination of parameters like R0, R∞, and α, which are used to calculate bioimpedance and assess conditions like oedema.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If plotting and extrapolation techniques are used to determine impedance values, then measurement precision is improved, but device complexity and computational requirements increase
Solution Approach 1:
The patent transforms the complex plotting and extrapolation problem into a simpler parameter estimation problem by changing the mathematical approach. Instead of plotting impedance values and performing graphical extrapolation, the invention uses parameter estimation techniques that directly calculate impedance values from measured data, reducing computational complexity while maintaining accuracy
Solution Approach 2:
The patent replaces the mechanical plotting process (graphical methods requiring plot generation and visual extrapolation) with an automated computational algorithm. This substitution eliminates the need for complex graphical processing and enables real-time calculation on portable devices with limited computational resources
2Measurement precision
If plotting and extrapolation techniques are used to determine impedance values, then measurement precision is improved, but productivity decreases due to real-time analysis difficulty
Solution Approach 1:
The patent changes the computational parameters from complex plotting operations to direct parameter estimation calculations. This transformation enables real-time processing by replacing iterative graphical methods with efficient algebraic computations that can be performed rapidly on portable devices
Solution Approach 2:
The patent performs preliminary data processing and transformation of raw impedance measurements into a format suitable for direct parameter estimation. This preliminary action prepares the data in advance, enabling faster real-time analysis without requiring complex plotting and extrapolation operations during the measurement phase
Data Source
AI summary
A method of determining parameter values used in impedance analysis of a subject. The method includes using a processing system to determine a number of impedance measurements at a corresponding number of frequencies. The impedance measurements are used to determine estimates of parameter values, with the estimates being used to determine theoretical impedance values based on the parameter value estimates. The theoretical impedance values are compared to the measured impedance values to allow a modification direction to be determined for at least one of the parameter value estimates. This is then used to modify at least one parameter value estimate, with the parameter values being determined at least in part from one or more modified parameter value estimates.