Optoelectronic Sensor for Non-Invasive Venous Oxygen Saturation
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Solution Overview
Problem
Current methods for determining venous oxygen saturation in human extremities are invasive and unable to non-invasively record and analyze movement and heart-synchronous blood perfusion changes during active or passive muscle work.
Innovation Solution
A device with at least one radiation source generating radiation at multiple wavelengths, a detector to receive backscattered or transmitted radiation, and evaluation electronics with a filter unit to selectively determine DC and AC components of venous blood volume changes, enabling non-invasive determination of venous oxygen saturation during passive or active limb movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If invasive methods are used to determine venous oxygen saturation, then measurement precision is improved, but ease of operation deteriorates
Solution Approach 1:
The patent replaces invasive mechanical/chemical measurement systems with an optoelectronic system that uses light sources and detectors to measure venous oxygen saturation non-invasively through photoplethysmography, eliminating the need for blood sampling while maintaining measurement precision
Solution Approach 2:
The patent introduces light as an intermediary medium that penetrates tissue to reach blood vessels, allowing indirect measurement of venous oxygen saturation through optical absorption properties of hemoglobin without direct contact with blood
2Loss of information
If movement-correlated blood volume changes are measured, then information about venous hemodynamics is improved, but signal complexity increases
Solution Approach 1:
The patent segments the complex photoplethysmographic signal into distinct components: a DC component representing baseline blood volume and an AC component representing pulsatile blood volume changes correlated with movement and heartbeat, allowing separate analysis of different hemodynamic parameters
Solution Approach 2:
The patent dynamically adapts the measurement system to capture blood volume changes that occur during movement, using the movement itself as a stimulus to enhance venous blood flow and improve the quality of hemodynamic information obtained
3Measurement precision
If multiple wavelengths are used for measurement, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent changes the wavelength parameter of the radiation source to use multiple discrete wavelengths (typically including red and infrared wavelengths) that correspond to the absorption characteristics of oxygenated and deoxygenated hemoglobin, enabling differentiation of oxygen saturation states through spectral analysis
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
Enables precise, non-invasive measurement of venous oxygen saturation and venous filling time, allowing for hemodynamic classification and simultaneous determination of arterial oxygen saturation, improving diagnostic capabilities for peripheral vascular diseases.
Implementation Method 1
The methodological basis of PPG is the fact that selective light in the visible or near-infrared range is absorbed much more strongly by hemoglobin and blood than by tissue
Implementation Method 2
selective light in the visible or near-infrared range is absorbed much more strongly by hemoglobin and blood than by tissue
Data Source
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AI summary
The device has a light detector connected with a control- and evaluation electronic system for analyzing detector output signals. A sensor is designed to a flatter and flexible design such that adaptation of the sensor is guaranteed to a selected tissue area profile and perfusion signal detection is carried out in reflection- and transmission modes. Venous direct current (DC)- and alternating current (AC) proportions of motion correlated blood volume changes are determined with measurement wavelengths to allow determination of oxygen saturation in trans-illumination venous volume of tissue. The light detector receives reflected light, and the sensor comprises two selectively light sources. An independent claim is also included for a method for non-invasive determination of dermal-venous oxygen supply in peripheral leg areas.