Optical Vital Signs Sensor Color Converting Plate
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Solution Overview
Problem
Existing optical vital signs sensors face inefficiencies in detecting vital signs due to reflectance losses and scattering of light at the skin surface, which affect the quality and accuracy of heart rate and blood volume fraction measurements.
Innovation Solution
The implementation of a color converting plate with a long-wave pass filter coating and a diffusing chamber in the optical vital signs sensor, which recycles unconverted light and reduces reflectance losses by transmitting long wavelengths while reflecting short wavelengths, enhances the sensor's efficiency and accuracy by improving light penetration and absorption measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional light source is used in the optical sensor, then the device structure is simple, but light is lost due to reflectance and scattering at the skin surface, reducing measurement accuracy
Solution Approach 1:
The patent changes the wavelength parameter of light by using a color converting plate that converts blue light (430-470nm) to green light (500-560nm). This wavelength transformation allows the light to better penetrate skin tissue and reduces reflectance losses, thereby improving measurement accuracy while reducing energy loss.
Solution Approach 2:
The color converting plate acts as an intermediary between the blue light source and the skin tissue. It converts the wavelength of light to optimize penetration and reduce reflectance, serving as a mediator that improves the interaction between light and tissue without requiring a change in the light source itself.
2Measurement precision
If a color converting plate is added to convert light wavelength, then light penetration and measurement accuracy are improved, but the device complexity increases
Solution Approach 1:
The color converting plate is integrated directly with the light source assembly, merging the wavelength conversion function into the existing sensor structure. This combination approach improves measurement accuracy while minimizing the increase in device complexity by consolidating functions rather than adding separate components.
3Productivity
If unconverted light is not recycled, then the device structure is simple, but optical energy is wasted and measurement efficiency is reduced
Solution Approach 1:
The patent recovers unconverted blue light that would otherwise be wasted by redirecting it through the diffusion chamber back toward the skin tissue. This recovery process improves measurement efficiency by utilizing previously lost optical energy without requiring a fundamentally new device architecture.
Solution Approach 2:
The diffusion chamber creates a feedback mechanism where unconverted light is redirected back into the measurement path. This feedback loop ensures that optical energy is utilized more efficiently, improving measurement efficiency while maintaining a relatively simple device structure.
4Loss of energy
If a diffusion chamber is added to recycle light, then optical efficiency is improved, but the device complexity and size increase
Solution Approach 1:
The diffusion chamber is integrated into the existing sensor housing, merging the light recycling function with the device enclosure. This integration reduces optical losses while minimizing the increase in device complexity by combining multiple functions within a unified structure.
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 enhances the optical efficiency of the sensor, leading to improved detection of heart rate and blood volume fraction, with reduced optical losses and increased accuracy in vital sign monitoring, allowing for non-invasive and reliable measurements.
Implementation Method 1
the color converting plate comprises a long-wave pass filter coating or film which is able to transmit light having a long wavelength while reflecting light having short wavelengths
Implementation Method 2
The emitted light is scattered in the skin and is at least partially absorbed by the blood
Implementation Method 3
The emitted light is scattered in the skin
Implementation Method 4
Part of the light exits the skin and can be captured by a photodiode
Data Source
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AI summary
An optical vital signs sensor is provided. The optical vital signs sensor is configured to measure or determine vital signs of a user. The optical vital signs sensor comprises a contact surface (101) and at least one light source (110) configured to generate light. The light is directed towards a skin (1000) of a user. Furthermore, at least one photo detector unit (120) is configured to detect light which is indicative of a reflection of the light beam from the at least one light source (110) in or from the skin (1000) of the user. Between the light source and the contact surface, a color converting plate (200) is provided which converts a color of the light from the light source.