16. Theory of Operation
16.1 Pulse Oximeter Theory
Dream Sock measures functional Oxygen Saturation of arterial Hemoglobin (SpO2) and Pulse Rate. Pulse oximetry measurements
are based on two physiological principles:
● The differences in optical absorbance properties between oxyhemoglobin (HbO2, oxygenated blood) and deoxyhemoglobin
(Hb, non-oxygenated blood)
● The volume (and therefore light absorption) of arterial blood changes due to heart pulsation as it is distributed in tissue
throughout the body.
A Pulse Oximeter determines the saturation of arterially perfused tissue by sequential illumination with the red and infrared
wavelengths of light via light emitting diodes (LEDs). Refer to the figure below. The time-varying signal passing through the tissue is
measured from a photodiode detector many times per second, and the differences between the maximum and minimum absorbance
due to pulsation are used to determine the saturation, and the pulsation time period is used to calculate the Pulse Rate.
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