Pulse Oximetry Sensor with Patterned Light Absorbing and Reflecting Materials
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Solution Overview
Problem
Pulse oximetry measurements are affected by outside light sources and heterogeneous tissue structures, leading to variability and inaccuracies in blood oxygen saturation readings due to the influence of large blood vessels, connective tissue, and dynamic structures.
Innovation Solution
The development of a pulse oximetry sensor with distinct light absorbing and reflecting materials on its tissue-contacting surface, where absorptive materials are placed near large vascular structures and reflective materials are placed near smaller vascular structures to minimize interference from outside light and tissue heterogeneities, ensuring accurate detection of light transmitted through perfused tissue.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a non-invasive sensor is used to measure blood oxygen saturation, then the measurement can be performed without invasive procedures, but outside light sources and heterogeneous tissue structures cause measurement variability and inaccuracies
Solution Approach 1:
The sensor applies different optical properties to different regions of its tissue-contacting surface. Specifically, it includes both light-absorbing regions and light-reflecting regions arranged in a pattern that corresponds to the heterogeneous structure of underlying tissue. This local differentiation allows the sensor to compensate for variations in tissue composition and outside light interference while maintaining non-invasive measurement capability.
2Reliability
If light is transmitted through heterogeneous tissue containing large blood vessels, bones, and connective tissue, then pulse oximetry measurements can be obtained, but the heterogeneous structures cause measurement variations unrelated to blood constituent amounts
Solution Approach 1:
The patent converts the harmful effect of heterogeneous tissue structures and outside light into a beneficial compensation mechanism. By incorporating both absorbing and reflecting regions in specific patterns, the sensor design acknowledges that light will interact with various tissue structures and uses this interaction to its advantage. The patterned arrangement allows the sensor to differentiate between light attenuation caused by blood constituents versus attenuation caused by bones, connective tissue, or outside light sources, thereby converting the problem of tissue heterogeneity into a means for improving measurement accuracy.
3Adaptability or versatility
If outside light sources are present during measurement, then the sensor can operate in various lighting conditions, but outside light leaks into the sensor causing detection of light not related to blood constituent amounts
Solution Approach 1:
The sensor divides its tissue-contacting surface into distinct functional segments: light-absorbing regions and light-reflecting regions. This segmentation allows the sensor to process different portions of the light signal separately. The absorbing regions minimize the impact of outside light by preventing it from reaching the detector, while the reflecting regions capture and redirect light that has passed through the tissue. This segmented approach enables the sensor to maintain accurate measurements even when outside light sources are present.
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 design reduces measurement variability and motion artifacts, providing a more linear relationship between light transmission and blood oxygen saturation, resulting in more accurate and reliable pulse oximetry readings.
Implementation Method 1
an emitter disposed on the sensor body, wherein the emitter is adapted to transmit light into tissue; a detector disposed on the sensor body, wherein the detector is adapted to detect the light
Implementation Method 2
a light absorbing material disposed on a second portion of the tissue-contacting surface of the sensor body
Implementation Method 3
a light reflecting material disposed proximate to the emitter and detector on a first portion of a tissue-contacting surface of the sensor body
Data Source
AI summary
A sensor may be adapted to account for factors that cause irregularities in sensor measurements. A sensor may selectively absorb light from outside sources. A sensor may selectively absorb light near a region of tissue having relatively large subcutaneous anatomic structures, such as large blood vessels, and selectively reflect light near a region of tissue that is relatively free of large blood vessels or other structures. The sensor is adapted to reduce the effect of large subcutaneous anatomic structures and outside light on measurements for pulse oximetry or other spectrophotometric techniques.