Dynamic Voltage Scaling for PPG LED Power Optimization
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Solution Overview
Problem
Conventional photoplethysmography (PPG) systems consume significant power due to the use of static voltage supplies for light-emitting diodes (LEDs), leading to reduced battery life in wearable devices, as they apply the same voltage level across different LEDs despite varying requirements.
Innovation Solution
Implementing dynamic voltage scaling (DVS) in PPG devices, where the voltage across LEDs is adjusted based on the specific LED being powered, using a buck boost converter controlled by a microcontroller unit (MCU) to apply optimal voltages for each measurement, reducing power consumption by minimizing surplus voltage dissipation as heat.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If static voltage supply is used for LEDs in PPG systems, then circuit simplicity is maintained, but power consumption increases due to surplus voltage dissipation as heat
Solution Approach 1:
The patent implements dynamic voltage scaling by adjusting the voltage supplied to LEDs based on their specific requirements. The system transitions from a static voltage supply to a dynamic one that can provide different voltage levels (e.g., 2.8V for green LED, 1.8V for red LED) to each LED, thereby reducing power consumption while maintaining measurement accuracy.
Solution Approach 2:
The patent applies different voltage levels to different LEDs based on their individual characteristics. Each LED receives a customized voltage supply optimized for its specific requirements, rather than using a uniform voltage for all LEDs. This local optimization reduces overall power consumption in the PPG system.
2Measurement precision
If higher voltage is applied to LEDs to ensure sufficient light output, then measurement quality is improved, but power consumption increases
Solution Approach 1:
The patent changes the voltage parameter supplied to each LED based on its specific requirements. By optimizing the voltage level for each LED (e.g., providing exactly 2.8V to green LED and 1.8V to red LED), the system ensures sufficient light output for accurate measurements while minimizing power consumption and avoiding excessive voltage dissipation as heat.
3Device complexity
If uniform voltage is applied to all LEDs, then device complexity is reduced, but power efficiency deteriorates due to surplus voltage dissipation
Solution Approach 1:
The patent implements dynamic voltage scaling that adjusts the voltage supplied to each LED based on its specific requirements. The system transitions from a static voltage supply to a dynamic one that can provide different voltage levels to different LEDs, thereby reducing power consumption while maintaining measurement accuracy.
Solution Approach 2:
The patent applies different voltage levels to different LEDs based on their individual characteristics. Each LED receives a customized voltage supply optimized for its specific requirements, rather than using a uniform voltage for all LEDs. This local optimization reduces overall power consumption in the PPG system.
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 reduces power consumption and extends battery life by dynamically adjusting voltages according to the needs of each LED, optimizing power usage in PPG systems.
Implementation Method 1
a light source (e.g., light emitting diode (LED))
Implementation Method 2
the photodetector measures light reflected from the tissue
Implementation Method 3
a buck boost converter controlled by a microcontroller unit (MCU) to apply optimal voltages for each measurement
Data Source
AI summary
Aspects of the disclosure relate to a device that includes a plurality of light sources comprising a first light source and a second light source configured to emit electromagnetic radiation. The device may be configured to determine to perform a first set of measurements on the subject within a time window, wherein the first set of measurements comprise a first measurement performed with the first light source using a first optimal voltage and a second measurement performed with the second light source using a second optimal voltage, wherein the first measurement and the second measurement are performed in a contiguous sequence within the time window, and wherein the first optimal voltage is different from the second optimal voltage. The device may be further configured to apply the first optimal voltage to the first light source and apply the second optimal voltage to the second light source.