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

Dangdang Shao, Chenbin Liu, Francis Tsow, Yuting Yang, Zijian Du, Rafael Iriya, Hui Yu, Nongjian Tao

Research output: Contribution to journalArticlepeer-review

78 Scopus citations


We present a noncontact method to monitor blood oxygen saturation (SpO2). The method uses a CMOS camera with a trigger control to allow recording of photoplethysmography (PPG) signals alternatively at two particular wavelengths, and determines the SpO2 from the measured ratios of the pulsatile to the nonpulsatile components of the PPG signals at these wavelengths. The signal-to-noise ratio (SNR) of the SpO2 value depends on the choice of the wavelengths. We found that the combination of orange (λ = 611 nm) and near infrared (λ = 880 nm) provides the best SNR for the noncontact video-based detection method. This combination is different from that used in traditional contact-based SpO 2 measurement since the PPG signal strengths and camera quantum efficiencies at these wavelengths are more amenable to SpO2 measurement using a noncontact method. We also conducted a small pilot study to validate the noncontact method over an SpO2 range of 83%-98%. This study results are consistent with those measured using a reference contact SpO2 device (r = 0.936, p < 0.001). The presented method is particularly suitable for tracking one's health and wellness at home under free-living conditions, and for those who cannot use traditional contact-based PPG devices.

Original languageEnglish (US)
Article number7275158
Pages (from-to)1091-1098
Number of pages8
JournalIEEE Transactions on Biomedical Engineering
Issue number6
StatePublished - Jun 2016


  • Physiological signal tracking
  • oxygen saturation
  • photoplethysmography (PPG)
  • remote sensing

ASJC Scopus subject areas

  • Biomedical Engineering


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