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Luminescence Lifetime Imaging of O2 with a Frequency-Domain-Based Camera System

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Illumination Adaptation in a Multi-Wavelength Opto-Electronic Patch Sensor.

Liangwen Yan¹, Yue Yu¹, Sijung Hu²

¹School of Mechatronic Engineering and Automation, Shanghai University, Shanghai 200444, China.

Sensors (Basel, Switzerland)

|August 23, 2020

Summary

This study developed an adaptive LED illumination system for photoplethysmography sensors. The system automatically adjusts light intensity for improved signal quality in heart rate and blood oxygen monitoring.

Keywords:

adaptive algorithm heart rate multi-wavelength opto-electronic patch sensor photoplethysmographic

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Area of Science:

Biomedical Engineering
Optoelectronics
Signal Processing

Background:

High-quality photoplethysmographic (PPG) signal acquisition relies on optimal illumination intensity.
Existing systems may lack dynamic control over light-emitting diode (LED) output, potentially compromising signal quality.

Purpose of the Study:

To develop and evaluate a controlled illumination intensity system for a multi-wavelength opto-electronic patch sensor.
To enable automatic adjustment of LED illumination based on real-time signal feedback.

Main Methods:

Designed a linear constant current source LED driver with an operational amplifier and series negative feedback.
Developed a linear regression model for rapid LED driver voltage determination.
Implemented a microcontroller-based adaptive algorithm to monitor photodetector signal quality and adjust individual LED array currents.

Main Results:

The system successfully controlled illumination intensities for a four-array, multi-wavelength LED sensor.
The adaptive algorithm effectively adjusted LED output based on received signal strength.
Demonstrated the ability to adapt LED illumination to signal quality, outperforming a non-adaptive approach.

Conclusions:

The developed adaptive illumination system enhances PPG signal acquisition by dynamically controlling LED output.
This approach offers improved reliability for monitoring vital signs like heart rate and blood oxygen saturation.
The adaptive circuitry and algorithm provide a robust solution for opto-electronic sensing applications.