Wrist-Worn Optical Sensor Chambers for Motion-Resilient Pulse Oximetry
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Solution Overview
Problem
Current pulse oximetry sensors require placement near significant capillary beds, such as fingers, ears, toes, nose, and forehead, which are inconvenient for everyday activities and unreliable during motion, limiting their use outside healthcare facilities.
Innovation Solution
A wearable device integrated into a wristwatch with a physiological monitoring sensor that includes a convex protrusion and light barriers/emitters/detectors configuration to measure pulse oximetry and other parameters at the wrist, utilizing algorithms for high-exertion motion environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pulse oximetry sensors are placed near significant capillary beds (fingers, ears, toes, nose, forehead), then measurement reliability is improved, but ease of operation deteriorates due to inconvenience for everyday activities
Solution Approach 1:
The patent applies local quality by selecting a specific measurement location (wrist) that differs from traditional capillary bed locations. The wrist sensor design incorporates local optical properties and tissue characteristics unique to the wrist area, enabling reliable measurements at this alternative site through optimized emitter-detector configurations tailored to wrist anatomy.
Solution Approach 2:
The wearable device achieves universality by enabling pulse oximetry measurements at multiple body locations, with the wrist being the primary innovative location. The sensor design can be universally applied to various everyday activity contexts (sports, daily routines, work), making the measurement system adaptable across different scenarios without requiring specialized placement at traditional sites.
2Measurement precision
If pulse oximetry sensors are placed at traditional locations (fingers, ears, toes, nose, forehead), then measurement precision is improved, but adaptability deteriorates for sporting activities and daily movement
Solution Approach 1:
The patent applies dynamics by designing a wrist-worn sensor that moves with the user's body during various activities. The sensor maintains functional contact with the wrist tissue through flexible mounting and compliant optical coupling, allowing it to dynamically adapt to wrist motion, deformation, and position changes during sports and daily activities while maintaining measurement precision.
Solution Approach 2:
The system employs parameter changes by utilizing multiple wavelengths of light and adjusting measurement parameters based on wrist-specific tissue optical properties. The sensor incorporates algorithms that adapt measurement parameters (wavelength selection, intensity, timing) to compensate for the different optical characteristics of wrist tissue compared to traditional measurement sites, maintaining precision across varying activity levels.
3Reliability
If motion algorithms are implemented for high-exertion environments, then reliability during motion is improved, but device complexity increases
Solution Approach 1:
The patent applies feedback by incorporating motion sensors (accelerometers, gyroscopes) that continuously monitor wrist movement and provide feedback to the optical measurement system. This feedback enables real-time compensation for motion artifacts, allowing the system to distinguish between signal changes caused by physiology versus those caused by movement, thereby maintaining reliability during high-exertion activities.
Solution Approach 2:
The system uses motion sensors as intermediaries between the physical motion and the optical measurement system. These intermediaries capture motion data and translate it into correction parameters that are applied to the pulse oximetry signals, effectively mediating the impact of motion on measurement accuracy without requiring direct modification of the optical path.
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
Enables reliable and convenient monitoring of physiological parameters like pulse rate, oxygen saturation, and hydration status at the wrist, suitable for everyday activities and sporting events.
Implementation Method 1
A first plurality of light emitting diodes (LEDs) configured to emit light of one or more wavelengths
Implementation Method 2
at least one detector that responds to the intensity of the optical radiation (which can be reflected from or transmitted through the tissue site) after absorption by pulsatile arterial blood
Implementation Method 3
The theoretical basis of this technique is the Beer-Lambert law, which states that the concentration ci of an absorbent in solution can be determined by the intensity of light transmitted through the solution
Data Source
AI summary
An optical physiological sensor can be integrated into a wearable device and can comprise a frame defining a first emitter chamber housing a first group of emitters; a second emitter chamber housing a second group of emitters; and a plurality of detector chamber housing a plurality of detectors configured to detect optical radiation emitted from the first and second groups of emitters.