Noncontact monitoring breathing pattern, exhalation flow rate and pulse transit time

Dangdang Shao, Yuting Yang, Chenbin Liu, Francis Tsow, Hui Yu, Nongjian Tao

Research output: Contribution to journalArticlepeer-review

152 Scopus citations


We present optical imaging-based methods to measure vital physiological signals, including breathing frequency (BF), exhalation flow rate, heart rate (HR), and pulse transit time (PTT). The breathing pattern tracking was based on the detection of body movement associated with breathing using a differential signal processing approach. A motion-tracking algorithm was implemented to correct random body movements that were unrelated to breathing. The heartbeat pattern was obtained from the color change in selected region of interest (ROI) near the subject's mouth, and the PTT was determined by analyzing pulse patterns at different body parts of the subject. The measured BF, exhaled volume flow rate and HR are consistent with those measured simultaneously with reference technologies (r = 0.98, p<0.001 for HR; r = 0.93, p<0.001 for breathing rate), and the measured PTT difference (30-40 ms between mouth and palm) is comparable to the results obtained with other techniques in the literature. The imaging-based methods are suitable for tracking vital physiological parameters under free-living condition and this is the first demonstration of using noncontact method to obtain PTT difference and exhalation flow rate.

Original languageEnglish (US)
Article number6824168
Pages (from-to)2760-2767
Number of pages8
JournalIEEE Transactions on Biomedical Engineering
Issue number11
StatePublished - Nov 1 2014


  • Mobile health
  • photoplethysmography (PPG),physiological signal detection
  • pulse transit time (PTT)
  • remote sensing
  • respiration

ASJC Scopus subject areas

  • Biomedical Engineering


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