A low-cost three-wavelength illumination system for camera-based photoplethysmography imaging

Area of Science:

• Biomedical Engineering
• Optical Sensing Technologies
• Medical Imaging

Background:

• Photoplethysmography imaging (PPGI) is a non-contact technique for cardiovascular monitoring.
• Existing PPGI systems often require complex and costly illumination setups.
• There is a need for cost-effective and reliable illumination solutions for PPGI research.

Purpose of the Study:

• To design and implement a low-cost, reliable three-wavelength illumination device for PPGI.
• To enable flexible spectral configurations for non-contact cardiovascular monitoring.
• To provide a robust solution for experimental and applied PPGI measurements.

Main Methods:

• Utilized high-power LEDs in green (520 nm), red (625 nm), and near-infrared (855 nm) spectral regions.
• Integrated a specific distribution of LEDs (7 green, 11 red, 15 infrared) for balanced camera sensitivity and uniform illumination.
• Employed independent LED drivers with pulse-width modulation (PWM) control and a microcontroller platform for precise operation.

Main Results:

• Achieved a cost-effective and reliable three-wavelength illumination system.
• Demonstrated compensation for wavelength-dependent camera sensitivity and uniform spatial intensity.
• Ensured stable operation, accurate timing, and synchronization for PPGI applications.

Conclusions:

• The developed illumination device is a robust and cost-effective solution for PPGI.
• Its compact, modular design facilitates integration with camera systems.
• Offers enhanced usability with optional wireless control for laboratory settings.