PPG Sensor Triggering and Disabling for Motion Artifact Reduction
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Solution Overview
Problem
Conventional wearable electronic devices face challenges in accurately detecting physiological characteristics due to motion artifacts in sensing signals, which reduce the accuracy of extracted respiration signals from ECG or PPG signals.
Innovation Solution
A mobile electronic apparatus with a sensor unit having first, second, and third sensing electrodes, where the PPG sensor is triggered to detect blood volume changes when a voltage difference is detected between the first and second electrodes, and disabled when the third electrode senses heart electrical activity, allowing the processing unit to remove motion noise from the signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the PPG sensor continuously detects blood volume changes to obtain physiological characteristic information, then the detection capability is improved, but motion artifacts increase and reduce measurement accuracy
Solution Approach 1:
The patent introduces an intermediary mechanism (motion detection algorithm and signal quality assessment) between the PPG sensor and the physiological characteristic extraction process. This intermediary detects motion artifacts and signal quality, then dynamically adjusts or disables PPG sensing during high-motion periods, preventing motion noise from corrupting the physiological measurements.
Solution Approach 2:
The patent implements dynamic control of the PPG sensor based on real-time motion detection and signal quality assessment. The system transitions between different operational states (continuous monitoring, intermittent sampling, or disabled) according to the detected motion level, optimizing the balance between detection capability and noise reduction.
2Measurement precision
If multiple sensing electrodes and sensors are used to improve detection accuracy, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent designs the sensor unit with multi-functionality, where the same sensing electrodes and processing unit serve multiple purposes: detecting voltage differences for motion detection, acquiring ECG signals for physiological monitoring, and controlling PPG sensor operation. This universal approach reduces overall device complexity while maintaining high measurement precision through coordinated multi-sensor operation.
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 enables efficient and precise detection of physiological characteristics by distinguishing and filtering out motion noise from the PPG and ECG signals, improving the accuracy of heart rate, pulse, and respiration rate measurements.
Implementation Method 1
The PPG sensor senses a PPG signal and detects blood volume changes
Implementation Method 2
the third sensing electrode is triggered to detect electrical activity of a heart between the first and third sensing electrodes
Data Source
AI summary
A detecting system, a mobile electronic apparatus and a method for detecting a physiological characteristic thereof are provided. The mobile electronic apparatus includes a sensor unit, a PPG photoplethysmography (PPG) sensor, and a processing unit. The sensor unit has a first, second, and third sensing electrodes. The PPG sensor senses a PPG signal. The processing unit is coupled to the sensor unit and the PPG sensor. When the first and second sensing electrodes detect a voltage difference above a threshold, the PPG sensor is triggered to detect blood volume changes, and when the third sensing electrode is triggered to detect electrical activity of a heart between the first and third sensing electrodes, the PPG sensor is disabled by the processing unit.