PPG Sensor Calibration via Reference Color Detection
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Solution Overview
Problem
Conventional electronic devices with biometric sensors do not effectively notify users of sensor damage or deterioration, leading to inaccurate readings and compromised sensor accuracy.
Innovation Solution
An electronic device with a photoplethysmogram (PPG) sensor that includes a light receiving module, LEDs, and photodiodes, equipped with a processor to determine if it is facing a reference color surface, perform tests, and calibrate the sensor based on received data to ensure accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the PPG sensor continuously operates without calibration, then the device simplicity is maintained, but the measurement precision deteriorates due to sensor damage or deterioration
Solution Approach 1:
The system performs preliminary calibration actions by detecting a reference color surface before actual biometric measurement. The processor identifies when the PPG sensor faces a surface with reference color (matching stored reference values) and automatically calibrates the sensor at this preliminary stage, ensuring accuracy is established before use rather than requiring continuous complex calibration systems.
Solution Approach 2:
The calibration system serves itself by automatically detecting when calibration is needed through reference color surface identification. The processor monitors the sensor environment, autonomously determines when calibration should occur, and executes the calibration process without requiring external intervention or complex continuous monitoring systems, making the simple act of placing the device on a surface with reference color triggers automatic calibration.
2Reliability
If the PPG sensor is tested frequently, then the reliability of sensor operation is improved, but the loss of time increases due to repeated testing and calibration
Solution Approach 1:
Instead of continuous or frequent calibration that would consume time, the system implements periodic calibration triggered by specific conditions - when the PPG sensor detects a surface with reference color. This periodic action ensures the sensor is calibrated at appropriate intervals based on actual usage conditions rather than on a fixed schedule, maintaining reliability while minimizing unnecessary calibration time.
3Measurement precision
If the device automatically calibrates the PPG sensor, then the measurement precision is improved, but the ease of operation deteriorates due to automatic calibration processes
Solution Approach 1:
The calibration process serves itself by automatically detecting when calibration is needed through reference color surface identification and executing the calibration without user intervention. The processor monitors the sensor environment, autonomously determines when calibration should occur, and performs the calibration in the background, making the system self-sufficient and eliminating the need for users to understand or initiate calibration procedures manually.
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 solution allows for the detection of sensor damage and calibration, ensuring accurate biometric readings and notifying users of sensor states, thereby maintaining measurement reliability.
Implementation Method 1
at least one light emitting diode (LED)
Implementation Method 2
at least one photodiode
Data Source
AI summary
Provided is an electronic device including a housing; a battery; a user interface; a photoplethysmogram (PPG) sensor including a light receiving module exposed through a portion of the housing, at least one light emitting diode (LED), and at least one photodiode; a processor operatively connected to the battery, the user interface, and the PPG sensor; and a memory. According to an embodiment, the memory stores instructions that, when executed, cause the processor to determine whether the PPG sensor is facing a surface of an external object having a reference color, determine whether to perform a test of the PPG sensor based on whether the PPG sensor is facing the surface, receive data from the PPG sensor by operating the PPG sensor in response to determining to perform the test, and perform calibration of the PPG sensor based on at least a portion of the received data. Other embodiments are possible.