Cardiac-Synchronized PPG Sensing for Low-Power Monitoring
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Solution Overview
Problem
Existing PPG monitoring systems face a trade-off between achieving accurate clinical measurements and reducing power consumption, as continuous uniform sampling results in redundant information and increased power consumption, while higher power allocation improves measurement quality but exceeds power limits.
Innovation Solution
A PPG monitoring system that controls the emission of optical radiation based on a cardiac value, such as average heart rate, to optimize power usage and reduce redundant sampling, allowing for more efficient power management without compromising accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If continuous uniform sampling is used to monitor PPG signals, then measurement precision is improved, but power consumption increases
Solution Approach 1:
The patent applies periodic action by controlling the optical radiation source to emit light in periodic pulses synchronized with the cardiac cycle rather than continuous emission. The control arrangement determines when to emit optical radiation based on detected cardiac activity, creating a periodic sampling pattern that matches the physiological rhythm. This reduces power consumption while maintaining measurement precision by focusing sampling on relevant cardiac phases.
Solution Approach 2:
The patent implements dynamics by making the sampling rate and optical emission dynamic rather than static. The system adjusts the timing and duration of optical radiation emission based on real-time cardiac data, allowing the monitoring parameters to adapt to varying heart rates and cardiac conditions. This dynamic approach optimizes the balance between measurement quality and power consumption.
2Measurement precision
If higher power is allocated to optical radiation sources, then measurement precision is improved, but device longevity decreases
Solution Approach 1:
By implementing periodic optical emission synchronized with cardiac cycles, the system concentrates power usage into brief, targeted pulses rather than continuous high-power emission. This periodic strategy maintains measurement precision during critical cardiac phases while allowing the device to operate at lower average power levels, thereby extending battery life and device longevity.
Solution Approach 2:
The system applies partial action by emitting optical radiation only during specific portions of the cardiac cycle when measurement is most valuable, rather than continuous emission. This selective timing ensures sufficient measurement precision is achieved during critical phases while reducing overall power consumption to preserve device longevity.
3Ease of operation
If uniform sampling rate is used, then ease of processing is improved, but power efficiency deteriorates
Solution Approach 1:
The system uses periodic sampling synchronized to cardiac cycles, which maintains processing simplicity by creating regularly patterned data intervals. While not completely uniform, the periodic nature based on cardiac rhythm provides a structured sampling framework that is easier to process than irregular sampling, while significantly improving power efficiency compared to continuous uniform sampling.
Solution Approach 2:
The system incorporates feedback by using detected cardiac data to control subsequent optical radiation emission timing. This feedback loop allows the system to adapt sampling rates to actual cardiac conditions, maintaining processing efficiency while optimizing power consumption based on real-time physiological information.
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 system achieves power-efficient PPG monitoring by selectively illuminating only portions of the cardiac cycle, ensuring accurate clinical value determination while conforming to power constraints, thus extending battery life and device longevity.
Implementation Method 1
PPG systems and devices use optical measurements to detect blood volume changes within a subject's tissue. One or more optical radiation sources are used to emit optical radiation to the subject's tissue, and then an optical detector is used to detect this radiation once it has interacted with the bodily tissue.
Data Source
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AI summary
Proposed concepts aim to provide methods and systems pertaining to a PPG monitoring system comprising a PPG sensor, a processing arrangement, and a control arrangement. In particular, the system is configured to control the emission of optical radiation from an optical source arrangement of the PPG sensor, based on a cardiac value determined from cardiac data that describes at least two cardiac cycles of the subject.