RF Motion Sensing for Stroke Volume and Respiratory Separation
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Solution Overview
Problem
Existing systems for determining physiological parameters like heart rate and respiratory rate using wearable RF sensors are limited by their inability to penetrate deep into the body, leading to reduced sensitivity and inability to quantify cardiac parameters such as stroke volume, as they rely on electrical changes near the skin surface rather than mechanical motion.
Innovation Solution
A system comprising an RF antenna module and a processor that uses a vector network analyzer to transmit and receive RF signals, providing a motion signal related to mechanical movements within the body, allowing for improved determination of physiological parameters by processing complex signals to separate cardiac and respiratory motions, thereby increasing sensitivity and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If wearable RF sensors are used to determine physiological parameters, then the measurement can be performed on the skin surface, but the RF radiation does not penetrate into deep structures like the heart, resulting in reduced sensitivity and inability to measure cardiac parameters
Solution Approach 1:
The patent changes the measurement parameter from electrical changes near the skin surface to mechanical motion detection. By using RF sensors to detect mechanical movements of structures within the body (such as heart motion), the system achieves both deep structure measurement capability and high sensitivity for cardiac parameter quantification including stroke volume
Solution Approach 2:
The patent replaces the electrical measurement approach with a mechanical motion detection approach. Instead of measuring electrical changes close to the skin, the system uses RF sensors to detect mechanical movements of internal structures, thereby enabling penetration depth improvement while maintaining measurement precision
2Adaptability or versatility
If electrical changes near the skin surface are measured, then the measurement setup is simple, but many different cardiac parameters such as stroke volume cannot be determined
Solution Approach 1:
The patent implements a universal measurement system that can determine multiple cardiac parameters including stroke volume, heart rate, and other physiological parameters using the same RF sensor setup. The system processes mechanical motion signals to extract various cardiac metrics, providing multi-functionality without requiring separate specialized devices for each parameter
3Reliability
If RF sensors measure electrical changes close to the skin, then the device can be worn by the subject, but the measurement sensitivity is reduced due to inability to sense deep mechanical motion
Solution Approach 1:
The patent replaces electrical field measurement with mechanical motion detection using RF sensors. This substitution enables the system to detect mechanical movements of deep structures while maintaining wearable form factor, thereby improving measurement reliability without sacrificing ease of operation and wearability
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 enhances the accuracy of determining heart-related and lung-related physiological parameters by directly measuring mechanical movements, allowing for precise quantification of parameters like stroke volume and respiratory rate with reduced influence from respiratory motion.
Implementation Method 1
an RF instrument connected to the RF antenna module and configured to transmit RF power into the RF antenna module, to receive an RF signal from the RF antenna module and to provide a motion signal that is related to a mechanical movement of a structure within the subject based on the received RF signal
Data Source
AI summary
The invention relates to a system 1 for determining a physiological parameter like a stroke volume of the heart of a subject 7. A measurement device includes a) an RF antenna module 3 with one or more RF antennas 4, 5 and b) an RF instrument 2 like a vector network analyzer configured to transmit RF power into the RF antenna module, to receive an RF signal from the RF antenna module and to provide a motion signal that is related to a mechanical movement of a structure within the subject based on the received RF signal. The physiological parameter is determined based on the provided motion signal and a model that provides, as an output, the physiological parameter if, as an input, the motion signal is provided.