Circuits and methods for photoplethysmographic sensors
First Claim
1. A method for processing a photoplethysmographic (PPG) signal in a monitoring device that measures a property of blood flow, the method comprising:
- causing one or more first light sources to emit light in the green wavelength spectrum during first periods of time;
causing one or more second light sources to collectively emit light in the red and infrared wavelength spectra during second periods of time different from the first periods of time;
obtaining a detected light signal from one or more detectors during the first and second periods of time, the detected light signal including pulsatile and non-pulsatile components;
obtaining a first digital signal representing the detected light signal;
generating, from the first digital signal, an offset control signal from an estimation of the non-pulsatile component;
generating a second digital signal by subtracting the offset control signal from the detected light signal to produce a subtracted signal and then applying a gain to the subtracted signal;
generating a reconstructed signal calculated from the gain, the second digital signal, and the offset control signal;
setting the offset control signal to zero while generating the reconstructed signal for each first period of time;
outputting data derived from portions of the reconstructed signal associated with the first periods of time as a heart rate; and
outputting data derived from portions of the reconstructed signal associated with the second periods of time as a blood oxygenation level.
1 Assignment
0 Petitions
Accused Products
Abstract
Some embodiments relate to a device, method, and/or computer-readable medium storing processor-executable process steps for processing a photoplethysmographic (“PPG”) signal in a monitoring device that monitors a property of blood flow. In some embodiments, the processing includes obtaining a first digital signal representing a detected light signal having a non-pulsatile (e.g., DC) component and a pulsatile component (e.g., AC). An offset control signal is generated from an estimation of the non-pulsatile component and a second digital signal is generated after subtracting the offset control signal from the detected light signal and applying a gain to the subtracted signal. A reconstructed signal is generated that is calculated from the gain and one or more of (i) the first digital signal, and (ii) the second digital signal and the offset control signal.
-
Citations
29 Claims
-
1. A method for processing a photoplethysmographic (PPG) signal in a monitoring device that measures a property of blood flow, the method comprising:
-
causing one or more first light sources to emit light in the green wavelength spectrum during first periods of time; causing one or more second light sources to collectively emit light in the red and infrared wavelength spectra during second periods of time different from the first periods of time; obtaining a detected light signal from one or more detectors during the first and second periods of time, the detected light signal including pulsatile and non-pulsatile components; obtaining a first digital signal representing the detected light signal; generating, from the first digital signal, an offset control signal from an estimation of the non-pulsatile component;
generating a second digital signal by subtracting the offset control signal from the detected light signal to produce a subtracted signal and then applying a gain to the subtracted signal;generating a reconstructed signal calculated from the gain, the second digital signal, and the offset control signal; setting the offset control signal to zero while generating the reconstructed signal for each first period of time; outputting data derived from portions of the reconstructed signal associated with the first periods of time as a heart rate; and outputting data derived from portions of the reconstructed signal associated with the second periods of time as a blood oxygenation level. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
-
-
16. A photoplethysmographic monitoring device, comprising:
-
one or more first light sources configured to emit light in the green wavelength spectrum; one or more second light sources configured to collectively emit light in the red and infrared wavelength spectra; one or more detectors; one or more processors; and a non-transitory, computer-readable medium storing instructions which, when executed, cause the one or more processors to; cause one or more first light sources to emit light in the green wavelength spectrum during first periods of time; cause one or more second light sources to collectively emit light in the red and infrared wavelength spectra during second periods of time different from the first periods of time; cause a detected light signal to be obtained from one or more detectors during the first and second periods of time, the detected light signal including pulsatile and non-pulsatile components; cause a first digital signal representing the detected light signal to be obtained; cause an offset control signal to be generated from an estimation of the non-pulsatile component in the first digital signal; cause a second digital signal to be generated by subtracting the offset control signal from the first digital signal to produce a subtracted signal and then applying a gain to the subtracted signal; cause a reconstructed signal to be calculated from the gain, the second digital signal, and the offset control signal; cause the offset control signal to be set to zero while generating the reconstructed signal for each first period of time; cause data derived from portions of the reconstructed signal associated with the first periods of time to be output as a heart rate; and cause data derived from portions of the reconstructed signal associated with the second periods of time to be output as a blood oxygenation level. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24)
-
-
25. A non-transitory computer-readable medium storing computer-executable instructions for processing a photoplethysmographic signal in a monitoring device that measures a property of a blood flow, the computer-executable instructions, when executed, causing one or more processors to:
-
cause one or more first light sources to emit light in the green wavelength spectrum during first periods of time; cause one or more second light sources to collectively emit light in the red and infrared wavelength spectra during second periods of time different from the first periods of time; cause a detected light signal to be obtained from one or more detectors during the first and second periods of time, the detected light signal including pulsatile and non-pulsatile components; cause a first digital signal representing the detected light signal to be obtained; cause an offset control signal to be generated from an estimation of the non-pulsatile component in the first digital signal; cause a second digital signal to be generated by subtracting the offset control signal from the first digital signal to produce a subtracted signal and then applying a gain to the subtracted signal; cause a reconstructed signal to be calculated from the gain, the second digital signal, and the offset control signal; cause the offset control signal to be set to zero while generating the reconstructed signal for each first period of time; cause data derived from portions of the reconstructed signal associated with the first periods of time to be output as a heart rate; and cause data derived from portions of the reconstructed signal associated with the second periods of time to be output as a blood oxygenation level. - View Dependent Claims (26, 27, 28, 29)
-
Specification