Symmetric LED Array for Pulse Oximetry Motion Error Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Pulse oximeters face errors due to motion-induced changes in optical efficiency and spectral variations of light sources, leading to inaccurate measurements and increased costs from calibration requirements.
Innovation Solution
The use of a sensor system with light sources symmetrically disposed and spectrally symmetrical about a central wavelength, allowing for improved optical coupling and eliminating the need for calibration models by combining LEDs with emission maxima at overlapping half power levels, thereby enhancing signal strength and reducing motion artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional pulse oximeters use single wavelength LEDs, then the device complexity is low, but measurement precision deteriorates due to motion-induced errors and spectral variations
Solution Approach 1:
The patent combines multiple LED light sources with different spectral characteristics (red LED at 660nm and infrared LED at 940nm) into a single sensor assembly. This merging allows the system to capture multiple wavelength signals simultaneously, improving measurement precision by compensating for motion-induced errors and spectral variations while maintaining a relatively simple device structure through integrated design
2Adaptability or versatility
If pulse oximeters use broader spectral content LEDs, then adaptability improves, but manufacturing precision deteriorates due to spectral variation
Solution Approach 1:
The patent implements a feedback mechanism where the sensor detects actual spectral content and intensity variations from LEDs, and the processor adjusts calibration parameters accordingly. This allows the system to adapt to manufacturing variations in LED spectral output, maintaining measurement accuracy across different production batches while supporting broader spectral content LEDs
Solution Approach 2:
The system dynamically changes calibration parameters based on detected LED spectral characteristics. By measuring the actual emission spectrum of each LED and adjusting the corresponding calibration factors, the system compensates for manufacturing precision variations while utilizing LEDs with broader spectral content for improved adaptability
3Measurement precision
If optical coupling efficiency is improved, then measurement precision improves, but ease of operation deteriorates due to sensitivity to motion
Solution Approach 1:
The patent employs asymmetric sensor design where multiple LEDs and photodetectors are positioned at different orientations and distances from the tissue interface. This asymmetric arrangement ensures that when motion occurs, not all optical paths are equally affected, allowing the system to maintain measurement precision while reducing sensitivity to specific motion patterns through differential signal processing
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 approach reduces motion-induced errors and allows for broader spectral content usage without calibration, improving the accuracy and cost-effectiveness of pulse oximeter readings.
Implementation Method 1
Pulse oximeters typically utilize a non-invasive sensor that transmits or reflects electromagnetic radiation, such as light, through a patient's tissue
Implementation Method 2
photoelectrically detects the absorption and scattering of the transmitted or reflected light in such tissue
Implementation Method 3
The first and third sources of electromagnetic radiation overlap at their half power level or greater and correspond to a center wavelength in the range of 650 to 670 nm
Data Source
AI summary
There is provided a sensor for pulse oximeter systems. The sensor comprises a first source of electromagnetic radiation configured to operate at a first wavelength, a second source of electromagnetic radiation configured to operate at a second wavelength, and a third source of electromagnetic radiation configured to operate at a third wavelength. The emission spectra of the first and third sources of electromagnetic radiation overlap at their half power level or greater and correspond to a center wavelength in the range of 650 to 670 nm.