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System for performing pulse oximetry

  • US 10,470,692 B2
  • Filed: 06/12/2015
  • Issued: 11/12/2019
  • Est. Priority Date: 06/12/2015
  • Status: Active Grant
First Claim
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1. A method for performing a pulse oximetry, the method comprising:

  • emitting, by at least one light source of a wearable device, a red signal and an infrared signal at a human tissue, the human tissue including a pulsatile tissue and a non-pulsatile tissue;

    detecting, by at least one optical sensor of the wearable device, a first signal, the first signal representing an intensity of a modulated red signal, the modulated red signal being generated by an interaction of the red signal with the human tissue;

    detecting, by the at least one optical sensor of the wearable device, a second signal, the second signal representing an intensity of a modulated infrared signal, the modulated infrared signal being generated by an interaction of the infrared signal with the human tissue;

    shifting, by at least one processor communicatively connected to the at least one optical sensor, the first signal by a first parameter Lred to account for a contribution to the first signal due to a reflection of the red signal from the non-pulsatile tissue;

    shifting, by the at least one processor, the second signal by a second parameter Lir to account for a contribution to the second signal due to a reflection of the infrared signal from the non-pulsatile tissue;

    determining, by the at least one processor and based on the shifted first signal and the shifted second signal, a ratio for obtaining an oxygen saturation;

    determining, by the at least one processor and based on the ratio, a value of the oxygen saturation;

    wherein Lred and Lir are positive arbitrary scalars pre-determined in a calibration process, the calibration process including determination of Lred and Lir based on a relationship log((IHred

    Lred)/(ILred

    Lred))/log((IHir

    Lir)/ILir

    Lir))=Rtrue, wherein Rtrue is a true ratio for obtaining the oxygen saturation, IHred is a maximum of the first signal, ILred is a minimum of the first signal, ILir is a maximum of the second signal, and IHir is a minimum of the second signal; and

    wherein the value of the oxygen saturation is used to provide reports on a symptom or a progression of one or more chronic diseases of a user.

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