Optical Sensor System for Absolute Tissue Oxygen Saturation
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Solution Overview
Problem
Current bedside monitoring devices are inadequate for accurately and continuously tracking tissue oxygenation status, particularly in detecting tissue hypoxia, which is crucial for managing various pathological conditions such as heart failure, diabetes, and vascular diseases.
Innovation Solution
An optical sensor system that includes an implantable or wearable device equipped with a light emitting and detecting portion, capable of measuring absolute tissue oxygen saturation (O2Sat) and total hemoglobin volume fraction (HbT) using multiple wavelengths, allowing for continuous monitoring and prediction of tissue hypoxia without direct measurement of tissue oxygen partial pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional pulse oximeters are used to measure oxygen saturation, then the device complexity is reduced, but the measurement precision is insufficient for accurately detecting tissue hypoxia and tracking patient status
Solution Approach 1:
The optical sensor system is divided into multiple independent light emitting portions (red and infrared LEDs) and light detecting portions (photodetectors), with each component optimized for specific wavelength detection. This segmentation enables precise measurement of oxygen saturation and total hemoglobin by separately measuring light absorption at different wavelengths, resolving the contradiction between measurement precision and device complexity.
Solution Approach 2:
The optical sensor system performs multiple functions simultaneously: measuring oxygen saturation (O2Sat), total hemoglobin concentration (HbT), and detecting tissue hypoxia. By integrating multiple measurement capabilities into a single sensor system, the patent achieves high measurement precision without proportionally increasing device complexity, as the same hardware infrastructure supports all measurements.
2Measurement precision
If direct measurement of tissue oxygen partial pressure is performed, then the measurement precision for oxygenation status is improved, but the device complexity and difficulty of measurement increase significantly
Solution Approach 1:
The patent uses optical absorption characteristics of hemoglobin as an intermediary to indirectly measure tissue oxygenation status. Instead of directly measuring oxygen partial pressure (which requires complex invasive sensors), the system measures light absorption at specific wavelengths, which correlates with oxygen saturation and hemoglobin concentration. This intermediary approach maintains measurement precision while dramatically reducing measurement difficulty.
Solution Approach 2:
The patent replaces mechanical/invasive oxygen sensing methods with optical measurement techniques. By substituting direct physical oxygen pressure measurement with optical absorption spectroscopy, the system achieves comparable or superior measurement precision through a non-invasive, easier-to-implement methodology that uses standard optical components.
3Measurement precision
If multiple wavelengths are used to measure both oxygen saturation and total hemoglobin, then the measurement precision and discrimination capability are improved, but the use of energy and device complexity increase
Solution Approach 1:
The optical sensor system uses periodic pulsing of light sources (LEDs) rather than continuous illumination. By alternating between light emission and detection phases, and using pulse-width modulation for multiplexing multiple wavelengths, the system reduces energy consumption while maintaining the ability to measure multiple parameters. The periodic action allows efficient use of the photodetectors and light sources without requiring continuous power delivery.
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 accurate and continuous monitoring of tissue oxygenation, allowing for early detection of hypoxia and discrimination between different physiological conditions, thereby improving patient management and therapy optimization.
Implementation Method 1
An optical sensor system that includes an implantable or wearable device equipped with a light emitting and detecting portion, capable of measuring absolute tissue oxygen saturation (O2Sat) and total hemoglobin volume fraction (HbT) using multiple wavelengths
Data Source
AI summary
A medical device for monitoring a patient condition includes a sensor capable of being advanced transvascularly to be positioned along a volume of tissue, the sensor including a first combination of a light source and a light detector to emit light into a volume of tissue and to detect light scattered by the volume of tissue and to generate a first output signal corresponding to an intensity of the detected light. A control module is coupled to the light source to control the light source to emit light at least four spaced-apart light wavelengths, and a monitoring module is coupled to the light detector to receive the output signal and compute a measure of tissue oxygenation using the light detector output signal.