Elastomeric Encapsulant with Light-Blocking Particles for PPG Sensors
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Solution Overview
Problem
Conventional photoplethysmography (PPG) sensors suffer from 'internal light pollution' due to unwanted stray light, which contributes to an unwanted DC component of the photoplethysmographic signal, and require separate optical barriers that increase sensor size and may not fit tightly with protective layers, leading to light leakage.
Innovation Solution
An apparatus with a light emitting means embedded in an elastomeric encapsulating medium, where at least a part of the surface is coated with a light blocking material to prevent light leakage, providing an integrated optical barrier that eliminates the need for separate barriers and ensures a tight fit with protective layers, reducing dimensions and light leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If separate optical barriers are added to block stray light, then internal light pollution is reduced, but device complexity and sensor size increase
Solution Approach 1:
The patent merges the optical barrier function with the encapsulating medium by embedding light-blocking particles directly into the encapsulant material. This integration eliminates the need for separate optical barrier components while maintaining effective stray light blocking, thereby reducing device complexity without sacrificing performance
2Object-affected harmful factors
If separate optical barriers are added to block stray light, then internal light pollution is reduced, but sensor size increases
Solution Approach 1:
The optical barrier functionality is merged into the encapsulating medium itself through embedded light-blocking particles. This integration allows the barrier function to be achieved within the existing sensor footprint without adding separate components that would increase sensor size
Solution Approach 2:
The encapsulating medium with embedded particles acts as a flexible, thin optical barrier layer that conforms to the sensor structure. This thin-film approach provides effective light blocking without the bulk associated with rigid separate barriers, maintaining compact sensor dimensions
3Object-affected harmful factors
If rigid optical barriers are used to block light, then light leakage is reduced, but fit with protective layers is poor leading to gaps
Solution Approach 1:
The encapsulating medium with embedded light-blocking particles provides a flexible barrier that can conform to protective layers and fill gaps, ensuring reliable sealing while maintaining optical blocking performance. The flexibility allows adaptation to manufacturing tolerances and assembly variations
4Object-affected harmful factors
If elastomeric encapsulating medium is used with embedded light-blocking particles, then light leakage is prevented and seal integrity is enhanced, but manufacturing complexity increases
Solution Approach 1:
The patent modifies the physical and optical parameters of the encapsulating medium by embedding light-blocking particles within it. This parameter change allows the medium to simultaneously provide mechanical sealing and optical blocking functions, eliminating the need for separate components and simplifying the overall manufacturing process despite the enhanced functionality
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 solution reduces internal light pollution, minimizes sensor size, and enhances the seal against dust and moisture, improving the signal-to-noise ratio by focusing light on the desired tissue area, reducing power consumption, and allowing for more compact and comfortable wearable devices.
Implementation Method 1
at least a part of a surface of the encapsulating medium is configured to prevent a leakage of light therethrough
Implementation Method 2
at least a part of a surface of the encapsulating medium is configured to prevent a leakage of light therethrough
Implementation Method 3
The optical coupling between the light emitting means and the protective layer is maintained despite the removal of the first optical barrier
Data Source
Figure 1~2
Figure 3~4
Figure 5A~5D
AI summary
Examples of the present disclosure relate to an apparatus for emitting light and a method for manufacturing the same. The apparatus comprises: a light emitting means embedded in an encapsulating medium, wherein at least a part of a surface of the encapsulating medium is configured to prevent a leakage of light therethrough. Some examples, though without prejudice to the foregoing, relate to an apparatus for use with a photoplethysmography sensor.