Non-invasive Cardiovascular Tissue State Detection via Multi-Frequency Bio-Impedance
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Solution Overview
Problem
Traditional bio-impedance and bio-reactance measurements are frequency-dependent and mixed with surrounding tissue impedance, making it difficult to accurately represent cardiovascular state and body fluid characteristics.
Innovation Solution
A non-invasive method using multiple synchronous alternating currents at different frequencies generated by OFDM symbols, transmitted into the body, and processed to separate frequency domain signals, calculate resistances and capacitances, and estimate the state of target tissues using multi-chamber modeling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional bio-impedance and bio-reactance measurements are used, then non-invasive measurement of blood flow and body fluid levels is achieved, but the measurements are mixed with surrounding tissue impedance making it difficult to determine which impedance dominates
Solution Approach 1:
The patent divides the tissue into multiple RC chambers (typically two chambers: one for target tissue and one for surrounding tissue) and uses multi-frequency measurements to separately determine the impedance characteristics of each chamber. This segmentation allows the system to isolate target tissue impedance from surrounding tissue impedance, resolving the mixing problem in traditional single-frequency measurements.
Solution Approach 2:
The patent employs multiple frequency parameters (at least two different frequencies) to measure tissue impedance. By measuring impedance at different frequencies and analyzing the frequency-dependent behavior of RC chambers, the system can distinguish between target tissue and surrounding tissue characteristics, thereby separating mixed impedance signals.
2Reliability
If frequency-dependent impedance parameters are used, then indirect representation of cardiovascular state is achieved, but frequency-selectivity impairment occurs
Solution Approach 1:
The patent intentionally uses multiple frequency parameters to measure impedance and explicitly accounts for the frequency-dependent behavior of tissue RC chambers. By modeling the frequency response of each chamber and analyzing changes across frequencies, the system converts the previously harmful frequency-selectivity impairment into a useful diagnostic feature for assessing cardiovascular state.
3Adaptability or versatility
If mixed bio-impedance measurements are used, then general tissue state information is obtained, but the measurements vary with individuals and different tissue states making them poor candidates for representing body fluid and cardiovascular characteristics
Solution Approach 1:
The patent segments the total impedance into distinct RC chamber components (target tissue chamber and surrounding tissue chamber). By separately characterizing each chamber's impedance properties through multi-frequency measurements and fitting procedures, the system can specifically extract body fluid and cardiovascular information from the target tissue chamber, eliminating the variability introduced by surrounding tissues.
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
Accurately and reliably measures the state of body fluid and cardiovascular circulatory tissues by distinguishing cardiovascular system from surrounding tissues, providing precise health monitoring and elasticity verification.
Implementation Method 1
Bio-impedance and bio-reactance measurements as non-invasive methods to measure blood flow and body fluid levels have been widely explored
Implementation Method 2
conductors are measured by the conductance (reciprocal of resistance), while non-conductors can be measured by capacitance or permittivity
Implementation Method 3
According to Ohm's law, the tissue's conductance and capacitance can be computed from the multiple-frequency alternating currents
Data Source
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AI summary
Disclosed is a non-invasive method and system to detect characteristic information of body tissues, comprising applying multiple synchronous alternating currents at different frequencies to a human body, wherein these alternating currents are generated by an IFFT or OFDM method. After receiving alternating currents modulated by the human body, the received signals are demodulated through FFT or OFDM, and then the information of the cardiovascular system and surrounding tissues is extracted from carriers at specified frequencies. The information is separated from a cardiovascular circulatory system and surrounding tissues by performing a system recognition or channel estimation procedure. The resistances and capacitances of the cardiovascular system and its surrounding tissues are respectively calculated, and the calculated resistances and capacitances are utilized to represent the states of body fluid and cardiovascular circulatory tissues. Thus, the corresponding state information can be accurately and reliably acquired, and accurate measurement of a target tissue can be achieved.