PPG Heart Rate Sensing With Motion-Gated Irregularity Detection
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Solution Overview
Problem
Existing PPG sensors struggle to accurately detect irregularities in heart rate signals due to motion artifacts and noise, often requiring increased power consumption for improved accuracy.
Innovation Solution
A PPG sensor unit configured to use a sampling procedure to detect multiple occurrences of a given event in the measured signal, incorporating motion sensors to delay measurements in high-motion states and adjust sampling based on low-motion conditions, and employing multiple wavelength sensing to balance accuracy and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If PPG sensors increase power consumption to improve accuracy, then measurement precision is improved, but use of energy deteriorates
Solution Approach 1:
The PPG sensor operates in periodic measurement cycles, alternating between active sensing phases and low-power sleep modes. The system performs measurements at specific intervals rather than continuously, reducing overall power consumption while maintaining detection accuracy for irregular heart rate patterns through strategic sampling during relevant physiological events.
Solution Approach 2:
The sensor dynamically adjusts measurement parameters such as sampling rate, light source intensity, and integration time based on detected physiological conditions. During periods of irregular heart rate detection, the system increases measurement frequency and sensitivity, while during stable conditions, it reduces power consumption by lowering these parameters.
2Reliability
If PPG sensors continuously monitor heart rate signals, then reliability of detection is improved, but use of energy deteriorates
Solution Approach 1:
The system employs feedback mechanisms where detected physiological patterns inform subsequent measurement strategies. When irregular heart rate patterns are detected, the system increases monitoring intensity and frequency. During periods of normal rhythm, the system reduces measurement activity, thereby maintaining detection reliability while optimizing power consumption through adaptive response to physiological feedback.
Solution Approach 2:
The system performs preliminary assessments of heart rate patterns to identify potential irregularities before initiating full-scale continuous monitoring. This preliminary action allows the system to maintain high detection reliability by being ready to switch to continuous monitoring when needed, while spending most time in lower-power states during normal conditions.
3Measurement precision
If PPG sensors increase sampling frequency to reduce noise, then measurement precision is improved, but productivity deteriorates
Solution Approach 1:
The measurement process is segmented into different phases with varying sampling frequencies. High-frequency sampling is applied only during critical detection windows when irregular patterns are identified, while lower-frequency sampling is used during stable periods. This segmentation maintains signal quality and noise reduction effectiveness while reducing overall processing burden and extending battery life.
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 detection of irregular heart rate patterns by reducing noise interference and optimizing power usage, thereby improving measurement accuracy while conserving battery life.
Implementation Method 1
Photoplethysmogram (PPG) sensors can be used to determine physiological information of a user. In a basic form, a PPG device can employ one or more light sources and one or more light detectors.
Implementation Method 2
The light detector(s) can convert the measured light into an electrical signal indicative of the intensity thereof.
Data Source
AI summary
This relates to methods for measuring irregularities in a signal and corresponding devices. The devices can include a PPG sensor unit configured to detect multiple occurrences of a given event in the measured signal(s) over a sampling interval. In some instances, the device can register the occurrences of the events. In some examples, the device can include one or more motion sensors configured to detect whether the device is in a low-motion state. The device may delay initiating measurements when the device is not in a low-motion state to enhance measurement accuracy. Examples of the disclosure further include resetting the sample procedure based on one or more factors such as the number of non-qualifying measurements. In some examples, the device can be configured to perform both primary and secondary measurements, where the primary measurements can include readings using a set of operating conditions different from the secondary measurements.