Microlayer Optical Stack for Blood-Flow-Independent Oxygen Sensing
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Solution Overview
Problem
Conventional techniques for monitoring oxygen levels, such as fingertip pulse oximeters, rely on blood flow and can lead to inaccurate readings when perfusion is compromised.
Innovation Solution
An optical stack with a test sample and a first optical filter comprising multiple microlayers, each less than 500 nm thick, that converts excitation light to a different wavelength, allowing accurate sensing of oxygen levels in skin tissue without relying on blood flow, using fluorescence quenching by oxygen to determine optical intensity changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional pulse oximeters are used to monitor oxygen levels, then the measurement can be obtained, but the accuracy deteriorates when blood flow is compromised
Solution Approach 1:
The patent introduces a fluorescent sensor material as an intermediary that converts excitation light to emitted light at different wavelengths. This intermediary enables direct optical sensing of oxygen in skin tissue without requiring blood flow, resolving the contradiction between measurement accuracy and reliability under compromised perfusion conditions
Solution Approach 2:
The patent replaces the mechanical/blood-flow-dependent pulse oximetry system with an optical sensing system using fluorescence. The sensor material emits light that is sensitive to oxygen presence, substituting the mechanical circulation-based measurement with an optical field-based measurement that does not depend on blood flow
2Measurement precision
If a multilayer optical filter is used to separate wavelengths, then the spectral separation improves, but the device complexity increases
Solution Approach 1:
The optical filter is segmented into multiple thin microlayers (at least 20 layers), each with thickness less than 500 nm. This segmentation allows precise spectral separation of excitation and emitted wavelengths while maintaining a compact structure, achieving high measurement precision without excessive device complexity
Solution Approach 2:
The optical filter uses composite material structures with alternating layers of different materials (e.g., high-index and low-index materials) to achieve wavelength-selective transmission. This composite approach enables precise spectral separation through constructive and destructive interference, improving measurement precision while managing device complexity
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 non-invasive, accurate sensing and monitoring of oxygen levels by detecting changes in optical intensity due to oxygen presence, providing reliable readings independent of blood flow.
Implementation Method 1
The test sample is configured to convert at least a portion of an incident excitation light having an excitation wavelength to a converted light having a converted wavelength different from the excitation wavelength
Implementation Method 2
The plurality of microlayers has an optical transmittance T1≥20% at the excitation wavelength and at a first incident angle. The plurality of microlayers has an optical transmittance T2≥20% at the converted wavelength and at a second incident angle
Implementation Method 3
using fluorescence quenching by oxygen to determine optical intensity changes
Data Source
AI summary
An optical device for sensing a presence of an analyte in a person is provided. The optical device includes a light source, an optical stack, and a reader. The light source emits a first light having a first wavelength. The optical stack is placed on a skin of the person. The optical stack includes a sensor material and an optical filter. The sensor material emits a second light having a second wavelength when irradiated with the first light. An optical property of the second light is sensitive to the presence of the analyte. The optical filter is disposed on the sensor material and includes a plurality of microlayers numbering at least 10 in total. The optical filter has different first and second transmittances at the respective first and second wavelengths.