Concentric Optical Sensing Layout for Accurate PPG Detection
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Solution Overview
Problem
Existing optical sensing systems face challenges in accurately determining physiological information due to optical losses caused by system components, which affect the measurement of photoplethysmographic (PPG) signals.
Innovation Solution
The implementation of a concentric architecture for optical sensing, featuring a plurality of light detectors arranged in a concentric manner around light emitters, including both visible and infrared wavelength emitters. This architecture is enhanced by a selective transparent layer and a Fresnel lens with different optical properties for each wavelength range, allowing for improved light collection and measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a basic optical sensing system with light emitter and detector is used, then the system structure is simple, but optical losses occur affecting measurement accuracy
Solution Approach 1:
The optical sensing system is segmented into multiple functional components: multiple light emitters at different wavelengths (visible and infrared), multiple light detectors arranged concentrically, selective transparent layers for different wavelength ranges, and a Fresnel lens with multiple regions. This segmentation allows each component to be optimized for specific wavelength ranges and measurement functions, reducing overall optical losses and improving measurement accuracy.
Solution Approach 2:
A Fresnel lens with multiple regions is introduced as an intermediary optical element between the light emitters and detectors. The lens includes a first region for visible light and a second region for infrared light, each optimized for their respective wavelength ranges. This intermediary component efficiently directs and focuses light across different wavelength ranges, minimizing optical losses and improving signal detection accuracy.
2Measurement precision
If multiple wavelength emitters are added to improve measurement accuracy, then PPG signal measurement accuracy improves, but device complexity increases
Solution Approach 1:
Multiple light emitters operating at different wavelengths (visible and infrared) are merged into a single integrated optical sensing unit. The emitters are arranged in a compact configuration with detectors positioned concentrically around them. This merging allows the system to perform multiple measurement functions simultaneously while maintaining a unified, space-efficient structure that manages complexity through integration rather than separation.
Solution Approach 2:
The optical sensing unit is designed with multi-functionality to handle different wavelength ranges and measurement types within a single device. The Fresnel lens serves multiple functions by directing both visible and infrared light, while the concentric detector arrangement enables simultaneous detection of multiple wavelength ranges. This universal design reduces the need for separate specialized components, managing device complexity through versatile, multi-purpose elements.
3Productivity
If light detectors are positioned closer to light emitters to improve signal detection, then light detection efficiency improves, but optical interference between components increases
Solution Approach 1:
The Fresnel lens is divided into regions with different optical properties optimized for specific functions. The first region is optimized for visible light from visible light emitters, while the second region is optimized for infrared light from infrared light emitters. This local quality differentiation allows each region to efficiently handle its designated wavelength range, improving light detection efficiency while minimizing optical interference between different wavelength components through spatial and functional separation.
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 concentric architecture and associated methods enable more accurate and efficient measurement of PPG signals by minimizing optical losses and optimizing light detection, thereby improving the determination of physiological information such as pulse rate.
Implementation Method 1
a Fresnel lens can be located in a corresponding region of the first and second light emitters. The Fresnel lens can include a plurality of regions, such as a first region and a second region. The first region can be located in the field of view(s) of the first light emitter(s), and the second region can be located in the field of view(s) of the second light emitter(s).
Implementation Method 2
a selective transparent layer overlaying the plurality of light detectors. The selective transparent layer can include a plurality of first sections transparent to a second wavelength range (e.g., infrared wavelengths) and non-transparent to a first wavelength ranges (e.g., visible wavelengths).
Implementation Method 3
The light received by the light detector can be light that has returned (e.g., reflected or scattered) and exited the tissue.
Implementation Method 4
The light received by the light detector can be light that has returned (e.g., reflected or scattered) and exited the tissue.
Data Source
AI summary
An electronic device including optical sensing with a concentric architecture and methods for operation thereof is disclosed. The concentric architecture can include light detector(s) arranged in a concentric manner around light emitter(s). In some examples, at least one light emitter can be located in the center of the device, and each light detector can be located the same separation distance from the light emitter. Each light detector can be arranged such that the separation distance from the centrally located light emitter can be greater than the separation distance from another light emitter. Examples of the disclosure further include a selective transparent layer overlaying the light detector(s). The selective transparent layer can include section(s) transparent to a first wavelength range and non-transparent to a second wavelength ranges. In some examples, the selective transparent layer can further include section(s) transparent to the second wavelength range.