Venous Waveform Sensing for Electrode-Free HRV Assessment
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Solution Overview
Problem
Existing methods for assessing heart rate variability (HRV) face challenges in distinguishing sympathetic and parasympathetic nervous system responses due to overlapping frequency ranges and require contact electrodes, which are inconvenient.
Innovation Solution
A computing device equipped with a wearable piezoelectric sensor on the wrist detects vibrations from blood vessels to generate signals for HRV and respiratory rate analysis, allowing for the determination of heart rate and respiration rate variability without direct contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If contact electrodes are used to derive HRV from ECG, then measurement precision is improved, but ease of operation deteriorates due to inconvenience
Solution Approach 1:
The patent replaces the mechanical contact electrode system with an optical sensor system that detects venous waveform signals through photoplethysmography. The optical sensor measures blood volume changes in the venous system, from which HRV parameters are derived without requiring skin contact electrodes, thereby maintaining measurement precision while significantly improving ease of operation and user comfort
Solution Approach 2:
The patent introduces the venous waveform signal as an intermediary medium to indirectly measure HRV. Instead of directly measuring electrical heart activity through contact electrodes, the system uses optical detection of venous blood volume changes as a mediator to derive HRV parameters, eliminating the need for uncomfortable contact electrodes while preserving measurement accuracy
2Measurement precision
If frequency ranges of HRV are analyzed to distinguish sympathetic and parasympathetic responses, then measurement precision is improved, but reliability deteriorates due to overlapping frequency ranges
Solution Approach 1:
The patent transitions from analyzing only temporal frequency domains to incorporating spatial-temporal analysis of venous waveform morphology. By examining multiple dimensions including rise time, decay time, peak amplitude, and area under the curve of venous waveforms across different frequency bands, the system achieves more reliable differentiation of sympathetic and parasympathetic responses, overcoming the limitation of overlapping frequency ranges through multi-dimensional feature extraction
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
This method provides a convenient and accurate assessment of HRV, enabling better differentiation of sympathetic and parasympathetic responses and respiratory rate variability, suitable for evaluating treatment efficacy and diagnosing conditions such as PTSD, anxiety, depression, and other health issues.
Implementation Method 1
a sensor of a computing device generates a signal representing vibrations originating from a blood vessel of a subject
Data Source
Figure 1
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Figure 3A~3B
AI summary
An example method includes (a) generating, via a sensor of a computing device, a signal representing vibrations originating from a blood vessel of a subject, where the vibrations are indicative of heart beats and/or respirations of the subject; (b) using the signal to determine first times elapsed between respective pairs of consecutive heart beats indicated by the vibrations and/or second times elapsed between respective pairs of consecutive respirations indicated by the vibrations; and (c) using the determined first times elapsed to determine a heart rate variability of the subject and/or the determined second times elapsed to determine a respiration rate variability of the subject.