Optical Sensor Modules with Hourglass Windows for Selective PPG Pathways

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Solution Overview

Problem

Conventional PPG sensors collect light from multiple optical pathways, including those with low pulsatile blood flow, leading to increased noise and reduced signal quality due to the collection of photons from undesirable pathways.

Innovation Solution

The optical sensor module is designed with a housing that includes a third window overlying the optical detector, featuring an hourglass or elongated shape with curved sides to preferentially accept light from pathways with higher pulsatile blood flow while rejecting light from undesirable pathways, using opaque materials or light guiding structures to enhance signal-to-noise ratio.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If conventional PPG sensors collect light from multiple optical pathways to maximize photon collection, then the total light intensity increases, but the signal-to-noise ratio deteriorates due to inclusion of photons from low pulsatile blood flow pathways

Engineering Contradiction:

Improvephoton collectionVSAvoidsignal-to-noise ratio

Core Design Contradiction:

Quantity of substanceVSMeasurement precision

Solution Approach 1:

The detector window is designed with non-uniform optical properties, having different transparency regions that selectively transmit light from specific optical pathways. The window transitions from uniformly transparent to having localized transparent and opaque regions, allowing preferential collection of photons from pathways with high pulsatile blood flow while blocking photons from pathways with low pulsatile content

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The detector window is segmented into multiple regions with different optical transmission characteristics. These segments correspond to different optical pathways, allowing the sensor to collect light from multiple pathways simultaneously while selectively emphasizing pathways with higher pulsatile blood flow content

Inventive Principle:

Principle #1Segmentation

2Quantity of substance

If the detector window size is increased to collect more photons from desirable pathways, then the AC signal strength improves, but noise from undesirable pathways also increases

Engineering Contradiction:

Improvephoton collection from desirable pathwaysVSAvoidoptical noise

Core Design Contradiction:

Quantity of substanceVSObject-affected harmful factors

Solution Approach 1:

The detector window incorporates localized opaque regions that block light from specific directions corresponding to undesirable optical pathways. This allows the window to maintain large overall area for photon collection while having local opaque segments that filter out noise from pathways with low pulsatile blood flow

Inventive Principle:

Principle #3Local quality

3Ease of manufacture

If conventional sensors use simple rectangular or circular window shapes, then manufacturing is simplified, but the ability to selectively collect light from specific optical pathways is reduced

Engineering Contradiction:

Improvewindow fabricationVSAvoidoptical pathway selection

Core Design Contradiction:

Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The detector window features non-uniform transparency patterns including curved boundaries and opaque regions that can be integrated into standard manufacturing processes. These localized variations in optical properties enable selective pathway collection while maintaining compatibility with conventional window fabrication methods

Inventive Principle:

Principle #3Local quality

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

The hourglass configuration significantly improves the signal-to-noise ratio by collecting more photons from desirable pathways, reducing noise and enhancing the accuracy of PPG measurements, particularly during motion, by maintaining a higher AC/DC ratio and minimizing motion artifacts.

Implementation Method 1

an optical detector of a PPG sensor generates an electrical signal in the detection electronics that modulates in unison with the changing photon density

Methodology Applied

Scientific EffectPhotoelectric Effect: Photoelectric Effect

Implementation Method 2

The housing includes a third window of optically transparent material that overlies the optical detector... at least one of the first and second sides is curved inwardly... preferentially accept light from pathways with higher pulsatile blood flow while rejecting light from undesirable pathways

Methodology Applied

Scientific EffectOptical Pathway Selection:

Data Source

PatentEP3911231B1Optical sensor modules with selective optical pathways

Publication Date: 2025.09.03 YUKKA MAGIC LLC

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AI summary

An optical sensor module includes a housing, first and second optical emitters within the housing, and an optical detector within the housing that is positioned between the first and second optical emitters. The housing includes respective first and second windows of optically transparent material that overlie the first and second optical emitters, and also includes a third window of optically transparent material that overlies the optical detector. The third window includes opposite first and second ends and opposite first and second sides, and at least one of the first and second sides is curved inwardly. Both of the first and second sides of the third window may be curved inwardly such that the third window has an hourglass shape.