Inductive Sensing Signal Separation for Overlapping Physiological Signals
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Solution Overview
Problem
Existing inductive sensing systems struggle to reliably distinguish between different physiological signals, such as heart and lung activity, and to differentiate these from motion artefacts, leading to incorrect clinical diagnoses and unreliable measurements.
Innovation Solution
A system that processes electromagnetic signals by generating multiple candidate signals from different linear combinations of frequency and amplitude inputs, and applies a signal selection procedure based on pre-defined criteria to isolate signals pertaining to specific physiological sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If frequency-based signal separation is used to distinguish heart and lung activity, then signal separation is simplified, but measurement precision deteriorates when heart and breathing rate frequencies overlap
Solution Approach 1:
The patent transitions from single-dimension frequency-based separation to multi-dimensional signal processing by extracting multiple features including frequency, amplitude, waveform morphology, and temporal patterns. This dimensional expansion allows differentiation of overlapping signals through their distinct characteristics across multiple dimensions rather than relying solely on frequency separation.
Solution Approach 2:
The system dynamically adjusts analysis parameters and applies adaptive filtering techniques that modify processing characteristics based on the detected signal conditions. By changing parameters such as filter coefficients, analysis windows, and feature weighting, the system maintains measurement precision across varying heart rates and breathing patterns where frequency overlap occurs.
2Productivity
If motion artefact filtering is performed using frequency and waveform assumptions, then processing speed is maintained, but reliability deteriorates when artefact characteristics match physiological signals
Solution Approach 1:
The patent implements feedback mechanisms where the system continuously monitors signal characteristics and adjusts its filtering and separation strategies based on detected patterns. By comparing expected physiological signal patterns with actual measurements and iteratively refining the separation algorithm, the system maintains high reliability even when motion artefacts resemble genuine pulse signals, without requiring computationally intensive reprocessing.
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
Effectively separates and enhances desired physiological signals while suppressing undesired components, improving the accuracy of heart and lung activity measurements and reducing the impact of motion artefacts.
Implementation Method 1
The working principle of inductive sensing is based on Faraday's law. An oscillating primary magnetic field is generated by a generating loop antenna, and this induces, via Faraday's law, eddy currents in the tissue irradiated by the signals.
Implementation Method 2
The eddy currents generate a secondary magnetic field. The total magnetic field is then a superposition of the primary magnetic field and the secondary magnetic field.
Data Source
AI summary
A system (8) and method is for extracting from sensed induction signals, component signals pertaining to different physiological phenomena in the body. A resonator circuit (10) is oscillated at a certain frequency to generate an alternating electromagnetic field which is applied to a body to be investigated. This field induces secondary eddy currents in the body which interact with the primary magnetic field and alter at least the frequency and amplitude of the resonator circuit oscillating current. These changes in the current characteristics, in particular the frequency and amplitude, are measured and provide first and second input signals. A system (8) or method is provided by embodiments of the invention which is arranged to receive these input signals. A multitude of different composite or fused signals are then generated by the system, each formed from a different linear combination ratio of the two input signals. These are then assessed with a signal selection procedure to identify a best candidate signal for providing a measure or indication of a particular one or more physiological phenomena. This can be based on pre-defined selection criteria, for example relating to signal characteristics of the candidate signals.