With our clinical-grade wristband device, Biostrap can measure respiratory rate with an algorithm combining the following: 

  1. Changes in amplitude of the PPG signal: As someone inhales and exhales, we review the signal changes
  2. Heart Rate Variability: We also look at the the inter-beat variability captured through the device as someone breathes in and out

Please refer to this paper for a more detailed explanation: http://iopscience.iop.org/article/10.1088/0967-3334/37/4/610/meta