Optical Sensor Module Window Geometry for Cleaner PPG Signals

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Solution Overview

Problem

Conventional PPG sensors collect light from multiple optical pathways, including noisy and less desirable pathways, leading to increased optical noise and reduced signal quality due to insufficient photons from high-pulsatile blood flow pathways.

Innovation Solution

The optical sensor module is designed with an hourglass-shaped or partially opaque window configuration that preferentially accepts light from longer optical pathways with higher pulsatile blood flow while rejecting shorter pathways, using optically transparent and opaque materials 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 light collection, then the quantity of photons collected is improved, but the optical noise increases due to inclusion of noisy pathways

Engineering Contradiction:

Improvequantity of photons collectedVSAvoidoptical noise

Core Design Contradiction:

Quantity of substanceVSObject-affected harmful factors

Solution Approach 1:

The patent segments the optical detection area into multiple zones with different window configurations. The first detection area has a first window configuration that accepts light from first optical pathways, while the second detection area has a second window configuration that accepts light from second optical pathways. This segmentation allows selective collection of photons from different pathways, maximizing useful signal photons while excluding noisy photons from unwanted pathways.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the sensor module are given different local qualities through varying window configurations. The first and second detection areas have different window shapes, sizes, or positions that are optimized for their respective optical pathways. This local differentiation enables each region to preferentially accept light from desirable pathways while rejecting light from noisy pathways specific to that region.

Inventive Principle:

Principle #3Local quality

2Quantity of substance

If the optical detector window is made larger to collect more photons, then the quantity of photons collected is improved, but the signal-to-noise ratio deteriorates due to inclusion of longer pathways with lower pulsatile blood flow interaction

Engineering Contradiction:

Improvequantity of photons collectedVSAvoidsignal-to-noise ratio

Core Design Contradiction:

Quantity of substanceVSMeasurement precision

Solution Approach 1:

The detection area is segmented into multiple zones with different window configurations optimized for different optical pathway lengths. This allows the sensor to collect photons from both short and long pathways while maintaining distinct optical characteristics for each region, thereby preserving signal-to-noise ratio while increasing total photon collection.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces a spatial dimension by creating multiple detection areas with different window configurations at different positions. Instead of simply enlarging a single window, the system adds dimensional complexity by positioning windows at different locations and/or orientations, enabling selective photon collection from multiple optical pathways simultaneously.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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-based biometric measurements.

Implementation Method 1

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 are curved inwardly such that the third window has an hourglass shape

Methodology Applied

Scientific EffectOptical pathway selection through geometry: Geometry

Implementation Method 2

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

Methodology Applied

Scientific EffectOptical transparency and opacity: Absorption (EM radiation)

Data Source

PatentUS12471791B2Optical sensor modules with selective optical pathways

Publication Date: 2025.11.18 YUKKA MAGIC LLC

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.