Wearable PPG Optics With Dynamic Transmitter-Receiver Paths
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Solution Overview
Problem
Existing wearable devices face challenges in accurately collecting photoplethysmogram (PPG) data due to factors such as motion, ambient light, and varying skin properties, which affect signal quality.
Innovation Solution
A configurable PPG system that selects transmitter-receiver combinations based on signal strength, quality metrics, user movement, temperature, and power consumption, and adjusts wavelengths and orientations to optimize signal acquisition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed transmitter-receiver combination is used for PPG measurement, then the device structure is simple, but the signal quality deteriorates under varying conditions such as motion, ambient light, and different skin properties
Solution Approach 1:
The patent implements dynamic selection of transmitter-receiver combinations based on real-time signal quality metrics. The system evaluates multiple possible optical paths and adaptively switches between them according to current physiological conditions, motion levels, and ambient light conditions, transforming a static measurement system into a dynamic one that optimizes signal acquisition under varying conditions
Solution Approach 2:
The patent designs the wearable device with multiple transmitter and receiver elements that can serve different functions depending on conditions. The same optical components are used for both signal generation and quality assessment, and the system can operate in different measurement modes (reflection vs. transmission) using the same hardware, increasing versatility without proportionally increasing complexity
2Measurement precision
If multiple transmitter-receiver combinations are evaluated and selected based on signal quality metrics, then the measurement accuracy is improved, but the processing time and computational resources increase
Solution Approach 1:
The patent pre-establishes multiple transmitter-receiver combinations and their associated signal quality metrics before actual measurement begins. The system pre-processes reference signals and establishes baseline quality thresholds, so that during actual PPG measurement, the selection process relies on pre-computed criteria rather than performing full analysis in real-time, reducing processing delays
Solution Approach 2:
The patent implements a feedback mechanism where signal quality metrics are continuously monitored and used to dynamically adjust the selected transmitter-receiver combination. The system measures signal quality parameters (such as signal-to-noise ratio, pulse waveform quality) and uses this feedback to switch between pre-configured optical paths, enabling real-time optimization without requiring exhaustive re-evaluation of all combinations
3Reliability
If the system adapts to changing conditions by selecting different transmitter-receiver combinations, then the reliability of PPG measurement is improved, but the device complexity increases
Solution Approach 1:
The patent divides the optical measurement system into discrete, independently controllable transmitter and receiver elements. Each element can be independently activated or deactivated based on measurement requirements, allowing the system to segment the measurement task across multiple simple components rather than requiring one complex integrated solution. This modular segmentation enables reliable adaptation while keeping individual component complexity low
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
Enhances the accuracy and reliability of PPG signal measurement by adapting to changing conditions and user physiology, providing superior data quality across different scenarios.
Implementation Method 1
an optical transmitter and an optical receiver. The PPG system may select a transmitter-receiver combination based on a variety of factors
Data Source
AI summary
Methods, systems, and devices for optical signal measurement are described. A wearable electronic device may activate a first combination of optical sensors, the first combination of optical sensors including a set of transmitter sensors and a set of receiver sensors. In some cases, one or more optical sensor of the first combination of optical sensors may be positioned under a protrusion on an inner surface of the wearable electronic device. The device may measure, at the set of receiver sensors at a first time, one or more signals from the set of transmitter sensors, determine a signal quality metric associated with the one or more signals, and select a second combination of optical sensors for use at a second time based on the signal quality metric.