Concentric Optical Sensing Layout for Multi-Wavelength PPG Accuracy
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Optical sensing systems face challenges in accurately determining physiological information due to optical losses from system components, which affect the measurement of photoplethysmogram (PPG) signals, such as pulse rate, especially when trying to differentiate between different wavelengths of light.
Innovation Solution
A concentric architecture with multiple light detectors arranged around light emitters of different wavelengths, including a selective transparent layer and Fresnel lens, allows for dynamic channel association and optimized separation distances to enhance signal collection and reduce noise, enabling both primary and secondary measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a basic optical sensing system with a single light emitter and detector is used, then the device complexity is low, but the measurement precision deteriorates due to optical losses and inability to differentiate wavelengths
Solution Approach 1:
The optical sensing system is segmented into multiple functional components: multiple light emitters emitting at different wavelengths (e.g., 630nm, 850nm, 940nm), multiple light detectors arranged in a concentric pattern, selective transparent layers for wavelength-specific transmission, and Fresnel lenses for focused light delivery. This segmentation allows simultaneous multi-wavelength measurements to improve physiological parameter accuracy while managing optical losses through dedicated detection paths for each wavelength.
Solution Approach 2:
The patent transitions from a linear or planar arrangement to a three-dimensional concentric architecture where light detectors are positioned radially around the light emitters at optimized separation distances. This spatial dimensionality change enables simultaneous detection of reflected and transmitted light at multiple wavelengths, improving signal collection efficiency and measurement precision without proportionally increasing device complexity.
2Reliability
If multiple light detectors are arranged at different separation distances from light emitters, then the signal-to-noise ratio improves, but the device complexity increases
Solution Approach 1:
Different light detectors in the concentric array are positioned at locally optimized separation distances from the light emitters based on their specific detection requirements. Detectors closer to emitters capture stronger signals for certain wavelengths, while detectors at greater distances reduce noise for other measurements. This local optimization of detector positions within the unified concentric architecture improves overall reliability without requiring completely separate detection systems.
Solution Approach 2:
The concentric arrangement of light detectors serves multiple functions simultaneously: detecting reflected light, transmitted light, and light at different wavelengths through a single integrated structure. This multi-functional design improves signal-to-noise ratio across all measurement modes while avoiding the complexity of multiple independent detector arrays, as the same concentric structure adapts to different measurement requirements.
3Measurement precision
If a selective transparent layer is added to manage wavelength transmission, then the measurement precision improves, but the device complexity increases
Solution Approach 1:
Selective transparent layers are introduced as intermediary components between the light emitters and detectors, and between different optical paths. These layers are engineered to be transparent to specific wavelengths (e.g., transparent to 850nm and 940nm infrared light) while blocking other wavelengths, enabling wavelength-specific detection without requiring complex filtering at the detector level. This intermediary approach simplifies the overall system by managing wavelength differentiation through passive optical filtering rather than active electronic control.
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
This configuration improves the signal-to-noise ratio and accuracy of physiological measurements by effectively managing light transmission and detection across various wavelengths, enhancing the system's ability to capture detailed physiological data.
Implementation Method 1
In some examples, a Fresnel lens can be located in a corresponding region of the first and second light emitters
Implementation Method 2
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
a light detector can be included to receive light through an aperture and/or window. 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.