Vital Sign Detection Using Simultaneous Reflective and Transmissive Light
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing vital sign measurement technologies, particularly contact and remote photoplethysmography (PPG) devices, face challenges in achieving high signal-to-noise ratio and accuracy due to motion artifacts and ambient light disturbances, especially in critical healthcare situations where pulsatility is weak.
Innovation Solution
A wearable light source device that simultaneously detects light in different wavelength ranges using a single detector, combining reflective and transmissive PPG signals to enhance accuracy and robustness, with a control unit synchronizing light sources and filters to improve signal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If contact PPG devices are used to measure vital signs, then measurement accuracy is improved, but patient comfort and freedom of movement deteriorate due to direct attachment and cables
Solution Approach 1:
The patent replaces contact-based mechanical attachment with a non-contact optical system. A camera captures reflected light from the patient's skin, and image processing algorithms extract PPG signals without requiring physical contact. This substitution eliminates cables and direct attachment while maintaining measurement capability through optical reflection analysis.
Solution Approach 2:
The patent introduces ambient light as an intermediary medium to transmit physiological information. Instead of direct contact between sensor and tissue, ambient light reflects off the skin and carries PPG signals to the camera. This intermediary approach enables remote measurement while preserving signal integrity through careful filtering and processing of the reflected light.
2Ease of operation
If remote PPG devices are used to improve patient comfort, then freedom of movement is improved, but signal-to-noise ratio deteriorates due to lower signal quality
Solution Approach 1:
The patent extracts the useful PPG signal from the reflected ambient light by separating it from background noise. Image processing algorithms analyze temporal variations in reflected light intensity to isolate the cardiac-induced PPG waveform from other environmental disturbances. This extraction process recovers the weak physiological signal despite the challenging remote measurement conditions.
Solution Approach 2:
The system employs feedback mechanisms through advanced signal processing algorithms that continuously analyze and refine the extracted PPG signals. By monitoring signal quality metrics and adjusting processing parameters in real-time, the system compensates for the inherently lower signal-to-noise ratio in remote measurements, maintaining measurement reliability without requiring physical contact.
3Reliability
If contact PPG sensors are used to ensure reliable measurement, then measurement reliability is improved, but patient comfort deteriorates due to obtrusive attachment
Solution Approach 1:
The patent replaces mechanical contact sensors with an optical camera-based system. The camera captures reflected light from the skin surface, and computational algorithms extract reliable PPG signals without requiring physical attachment. This substitution maintains measurement reliability through robust optical detection while completely eliminating the discomfort associated with contact sensors and cables.
Solution Approach 2:
The system uses the patient's own skin as a reflective surface for ambient light, requiring no external attachment or preparation. The skin naturally reflects light and generates the PPG signal through blood volume changes, allowing the system to obtain reliable measurements passively without interfering with the patient's normal activities or requiring special positioning.
4Ease of operation
If non-contact remote PPG is used to eliminate cables and improve comfort, then ease of operation is improved, but measurement precision deteriorates due to motion artifacts and ambient light disturbances
Solution Approach 1:
The system employs feedback through advanced signal processing that continuously monitors and compensates for motion artifacts and ambient light variations. By analyzing temporal patterns in the reflected light and comparing them against expected PPG waveform characteristics, the algorithm distinguishes true physiological signals from environmental disturbances, maintaining signal quality despite the non-contact measurement approach.
Solution Approach 2:
The patent extracts the PPG signal from the complex background of ambient light and motion by focusing on specific temporal frequency characteristics. Image processing algorithms isolate the cardiac-induced oscillations from other movements and environmental variations, effectively separating the useful physiological information from interfering factors in the reflected light signal.
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 approach provides a higher signal-to-noise ratio and reduced artifacts, enabling more accurate and reliable vital sign measurements, even in challenging conditions, by leveraging the strengths of both reflective and transmissive modes.
Implementation Method 1
a light source for emitting light, wherein the light source is mounted in or at the holder such that the emitted light is transmitted through a region interest of the subject
Implementation Method 2
a detection unit configured for contactless detection of light in at least two different wavelength ranges from a region of interest of a subject, wherein said detection unit is configured to detect a first light portion in a first wavelength range from light reflected from said region of interest
Implementation Method 3
detect a second light portion detected in a second wavelength range from light transmitted through said region interest
Data Source
AI summary
A device, system and method for determining vital signs of a subject is presented that improves accuracy and reliability, the device comprising a detection unit for contactless detection of light in at least two different wavelength ranges from a region of interest of a subject, wherein said detection unit is configured to detect a first light portion in a first wavelength range from light reflected from said region of interest in response to illumination by a first light source and to detect a second light portion in a second wavelength range from light transmitted through said region interest in response to illumination by a second light source, wherein said detection unit is configured to detect said first light portion and said second light portion simultaneously in response to illuminations that are at least temporarily simultaneous and wherein said first wavelength range and said second wavelength range are different. A processing unit is provided for deriving plethysmography, PPG, signals from the detected light for said at least two different wavelength ranges. An analysis unit is provided for deriving a desired vital sign from the PPG signals for at least two different wavelength ranges.