Noncontact Monitoring of Blood Oxygen Saturation Using Camera and Dual-Wavelength Imaging System

Area of Science:

• Biomedical Engineering
• Optical Sensing
• Medical Devices

Background:

• Traditional pulse oximetry relies on contact-based sensors.
• Noncontact methods for monitoring blood oxygen saturation (SpO2) are needed for remote and continuous health tracking.
• Photoplethysmography (PPG) signals contain information about blood volume changes.

Purpose of the Study:

• To develop and validate a noncontact method for measuring SpO2 using a camera.
• To identify optimal wavelengths for noncontact PPG-based SpO2 detection.
• To assess the feasibility of the method for home-based health and wellness monitoring.

Main Methods:

• Utilized a CMOS camera with trigger control to capture PPG signals at two distinct wavelengths.
• Analyzed the ratio of pulsatile to nonpulsatile PPG signal components to determine SpO2.
• Investigated wavelength combinations, identifying orange (611 nm) and near-infrared (880 nm) for optimal signal-to-noise ratio (SNR).

Main Results:

• The orange (611 nm) and near-infrared (880 nm) wavelength combination yielded the best SNR for noncontact SpO2 measurement.
• A pilot study demonstrated strong correlation (r = 0.936) between the noncontact method and a reference contact SpO2 device.
• The method accurately measured SpO2 within a range of 83%-98%.

Conclusions:

• A noncontact, video-based SpO2 monitoring method using specific wavelengths is feasible and accurate.
• This technique offers a promising solution for remote health tracking and for individuals who cannot use conventional SpO2 devices.
• The chosen wavelengths are optimized for camera-based PPG signal acquisition, differing from traditional contact methods.