Earlobe Light Sensor for Motion-Resistant Heart Rate Monitoring
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Solution Overview
Problem
Existing heart rate monitoring devices are not suitable for continuous monitoring during exercise due to motion artifacts, which affect the accuracy of heart rate and SpO2 measurements, and are often uncomfortable or unreliable for wearers.
Innovation Solution
A noninvasive light sensor with a circular support member and multiple light emitters and detectors placed symmetrically around the circumference, such as in ear buds or arm bands, to minimize motion-induced noise and improve signal accuracy by using red and infrared light to detect heart rate and SpO2 levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional heart rate monitors use ECG type chest belt with wireless link, then accurate and reliable heartbeat detection is achieved, but user comfort deteriorates due to plastic belt on chest and dirt accumulation
Solution Approach 1:
The patent replaces the mechanical ECG chest belt system with an optical detection system using infrared LEDs and photodetectors. This substitution eliminates the need for contact with gel and plastic belts, improving user comfort while maintaining measurement capability through optical absorption spectroscopy of blood vessels in the earlobe.
Solution Approach 2:
The patent introduces the earlobe tissue as an intermediary medium between the light source and detector. The infrared light passes through the earlobe tissue where blood vessels absorb specific wavelengths, allowing indirect measurement of blood flow and heart rate without direct contact with the chest or use of uncomfortable belts.
2Ease of operation
If IR LED and IR sensor through ear lobe or finger tip are used, then user comfort is improved, but measurement reliability deteriorates due to motion artifact during exercise
Solution Approach 1:
The patent merges multiple infrared LEDs emitting at different wavelengths with multiple photodetectors in a single earlobe-mounted device. This combination allows simultaneous measurement of multiple physiological parameters (heart rate, SpO2, blood flow) and provides redundancy to compensate for motion artifacts through signal processing and comparison of multiple channels.
Solution Approach 2:
The patent utilizes changes in optical absorption parameters at different infrared wavelengths to distinguish between static tissue absorption and dynamic blood flow changes. By monitoring absorption at multiple wavelengths simultaneously, the system can differentiate between motion-induced changes and actual physiological changes, maintaining measurement reliability during exercise.
3Measurement precision
If finger pulse oximeter is used, then SpO2 measurement is achieved, but measurement accuracy deteriorates during exercise due to motion-induced blood volume changes
Solution Approach 1:
Instead of measuring light transmission through the entire finger as in traditional pulse oximeters, the patent inverts the approach by placing the light source and detector in close proximity on the earlobe surface, measuring reflected and scattered light from superficial blood vessels. This inversion reduces the path length through moving tissue and minimizes the impact of motion-induced blood volume changes.
Solution Approach 2:
The patent focuses the measurement on local superficial blood vessels in the earlobe rather than deep tissue throughout the finger. By targeting specific local regions with visible vasculature and placing sensors directly over these areas, the system achieves more stable measurements during motion as the local tissue geometry changes less during exercise compared to finger positioning.
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 enables accurate and continuous monitoring of heart rate and SpO2 during exercise by reducing motion-induced noise and improving signal quality, providing reliable feedback and data for users.
Implementation Method 1
A plurality of light emitters and light detectors are located about a circumference of the circular support member for respectively emitting light signals into different areas of tissue surrounding the body part, and receiving reflected light signals from the different areas of tissue surrounding the body part
Implementation Method 2
Measuring heartbeat rate and SpO2 (blood oxygenation) is based on the absorption of red and infrared light
Data Source
AI summary
A noninvasive light sensor for detecting heart beat signals has a circular support member engageable circumferentially with a body part of a person. There are a plurality of light emitters and light detectors located around a circumference of the circular support member for respectively emitting light signals into different areas of tissue surrounding the body part, and receiving reflected light signals from the different areas of tissue surrounding the body part.