Pulse Oximeter Light Source Control for Low-Power Signal Quality
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Solution Overview
Problem
Existing pulse oximeters, particularly those operated by batteries, face challenges in reducing power consumption without compromising the quality of oxygen saturation and pulse rate monitoring.
Innovation Solution
A method for controlling the light source of a pulse oximeter by adjusting the brightness and color based on the amplitude profile of the sensor signal, using a scaling factor to optimize the light source current, and implementing a control unit to execute this method.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the light source current is reduced to save power, then power consumption decreases, but the quality of the sensor signal deteriorates
Solution Approach 1:
The patent implements dynamic adjustment of the light source current based on real-time sensor signal quality assessment. The control unit continuously monitors signal characteristics and adapts the current level, transitioning from static to dynamic operation to maintain optimal signal quality while minimizing power consumption.
Solution Approach 2:
The system employs feedback control by evaluating the quality of the sensor signal and using this information to adjust the light source current. The control unit receives feedback about signal quality and modifies the current accordingly, creating a closed-loop control system that balances power consumption and signal quality.
2Measurement precision
If the light source current is increased to improve signal quality, then measurement precision improves, but power consumption increases
Solution Approach 1:
The patent changes the operating parameters of the light source dynamically by adjusting the current level based on signal quality requirements. Instead of operating at a fixed current level, the system modifies the current parameter in response to changing measurement conditions, enabling optimal performance across different operating states.
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 while maintaining the quality of photoplethysmogram readings, ensuring accurate oxygen saturation and pulse rate monitoring by dynamically adjusting the light source current in response to signal quality changes.
Implementation Method 1
a light sensor configured to convert a portion of light transmitted and/or reflected by a body part when irradiated with light from the light source into an (electrical) sensor signal
Data Source
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AI summary
A method for controlling a light source (3) of a pulse oximeter (1) comprises: receiving a sensor signal (11) generated by a light sensor (5) for detecting a light component transmitted and/or reflected by a body part (9) upon irradiation with light from the light source (3); receiving a current value (17) of at least one control parameter for controlling a brightness and/or color of the light source (3); determining a scaling factor from a temporal profile of an amplitude of the sensor signal (11), taking into account a target value for the amplitude; determining a new value for the at least one control parameter by multiplying the current value (17) by the scaling factor; applying the new value to the at least one control parameter.