Multichannel BCG Sensor Cepstrum Analysis for Heart IBI
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Solution Overview
Problem
Current non-contact ballistocardiographic (BCG) monitoring methods using single-channel pressure sensors lack accuracy and resolution for heart rate variability (HRV) analysis, and existing devices are cumbersome and invasive, making them impractical for continuous monitoring in everyday environments.
Innovation Solution
A multichannel pressure sensing sensor integrated into a bed mattress or wearable device, utilizing the cepstrum method with Discrete Fourier Transform (DFT) for short time windows to accurately measure heart inter beat interval (IBI) and analyze BCG signals, providing improved resolution and accuracy for HRV analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If single-channel pressure sensors are used for BCG measurement, then the device is simple and unobtrusive, but the accuracy and resolution for HRV analysis is inadequate
Solution Approach 1:
The sensor system is divided into multiple independent measurement channels (at least two channels) that can be processed separately. Each channel captures BCG signal components, and the system processes these segmented signals through cepstrum analysis to extract heart IBI with high precision, resolving the contradiction between simplicity and measurement accuracy.
Solution Approach 2:
The patent transitions from single-channel one-dimensional measurement to multi-channel multi-dimensional measurement. By adding the dimension of multiple simultaneous measurements and processing them through cepstrum transform, the system achieves superior HRV analysis accuracy without proportionally increasing device complexity.
2Measurement precision
If contact electrode ECG measurement is used, then accurate heart IBI measurement is achieved, but the device becomes complex and requires direct skin contact
Solution Approach 1:
The patent replaces the mechanical contact-based ECG electrode system with a non-contact pressure sensing system. Instead of requiring skin contact through cables, the system uses pressure sensors (can be integrated into mattresses or wearables) to detect BCG signals mechanically, eliminating the need for physical contact while maintaining measurement accuracy.
Solution Approach 2:
The patent introduces BCG signal as an intermediary between the heart's electrical activity and the measurement system. Rather than directly measuring electrical signals through electrodes, the system measures the mechanical pressure variations caused by heartbeats, which serve as an intermediary carrier of cardiac information that can be detected non-invasively.
3Measurement precision
If long time windows are used for Fourier Transform, then the variance in time domain is averaged, but time resolution decreases and individual heart IBI value cannot be detected
Solution Approach 1:
The patent employs dynamic time windowing where the analysis window adapts to the instantaneous heart rate and signal characteristics. Rather than using a fixed long window, the system adjusts the window duration based on the beating heart rate, allowing sufficient averaging for variance reduction while maintaining fine time resolution for individual IBI detection.
Solution Approach 2:
The system uses periodic cepstrum analysis that processes signal segments in a rhythmic manner synchronized with the heartbeat. By applying cepstrum transform to periodically sampled segments and accumulating results, the system achieves both variance averaging across periods and preservation of temporal resolution for each individual beat.
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 multichannel sensor system enables accurate and unobtrusive monitoring of heart IBI and HRV with high time resolution, overcoming the limitations of single-channel sensors and allowing for continuous, non-invasive monitoring in various settings, including during sleep and movement.
Implementation Method 1
measuring ballistocardiographic signal (BCG) using a multichannel sensor
Implementation Method 2
single channel pressure sensitive sensors in a bed mattress
Implementation Method 3
applying Discrete Fourier Transform (DFT) for short time windows
Implementation Method 4
analyzing this multichannel data with a cepstrum method for heart inter beat interval (heart IBI) and heart rate variability (HRV) calculation
Data Source
AI summary
A monitoring apparatus comprising a multichannel pressure sensing sensor for measuring a ballistocardiographic signal of a human body is provided. The monitoring apparatus comprises a manner for selecting a time window for heart inter beat interval including two consecutive heart beats to be estimated, defining a spectrum for the signal averaging between at least two measurement channels of the sensor, a cepstrum from the logarithm of the spectrum, and a heart inter beat interval. A method for defining a heart inter beat interval is also provided, where a ballistocardiographic signal of a body is measured with a multichannel pressure sensing sensor, a time window for heart inter beat interval including two consecutive heart beats to be estimated is selected, a spectrum for the signal averaging between at least two measurement channels of the sensor, a cepstrum from the logarithm of the spectrum, and a heart inter beat interval are defined.