We are interested in the waveforms.

  1. Pulsatile physiological waveform (AC, ~1Hz): cardiac synchronous changes
  2. Slow varying baseline (DC): respiration, sympathetic nervous system activity, thermoregulation

The important factors are

  1. blood volume,

  2. blood vessel wall movement,

  3. orientation of red blood cells (RBC),

  4. absorption: 1

    1. Optical water window: Absorbs ultraviolet and infrared; melanin also absorbs shorter wavelengths,
    2. Isobestic wavelength,
    3. Tissue penetration depth,
  5. multi-bilateral site photoplethysmography

Pulse Wave

  1. Pulse distortions and alterations at the periphery
  2. Damage and disease in the vascular

References and Notes

  1. Allen, J. (2007). Photoplethysmography and its application in clinical physiological measurement. Physiological Measurement, 28(3), 0–39. ↩︎

Planted: by ;

Lei Ma (2020). 'Photoplethysmography', Intelligence, 10 April. Available at: