US 11,937,923 B2
Non-invasive method to determine blood oxygen saturation level
Paul Edouard, Issy les Moulineaux (FR); and Romain Kirszenblat, Issy les Moulineaux (FR)
Assigned to WITHINGS, Issy les Moulineaux (FR)
Filed by WITHINGS, Issy les Moulineaux (FR)
Filed on Apr. 30, 2021, as Appl. No. 17/245,139.
Claims priority of application No. 20305419 (EP), filed on Apr. 30, 2020.
Prior Publication US 2021/0338118 A1, Nov. 4, 2021
Int. Cl. A61B 5/1455 (2006.01); A61B 5/00 (2006.01)
CPC A61B 5/14551 (2013.01) [A61B 5/0004 (2013.01); A61B 5/681 (2013.01); A61B 5/7225 (2013.01); A61B 5/7264 (2013.01); A61B 5/721 (2013.01)] 24 Claims
OG exemplary drawing
 
1. A method to determine a current functional blood oxygen saturation level, the method comprising:
acquiring, at a predefined sampling frequency, a photoplethysmography light response for each wavelength of a plurality of at least three wavelengths, resulting respectively in a first, second and third raw data series representing an amplitude response through a user's tissue,
applying a low-pass filter to each of the first, second and third raw data series, resulting respectively in a first, second and third DC data series representing an unmodulated amplitude response,
applying a high-pass filter to each of the first, second and third raw data series, or subtracting respectively first, second and third DC data series to said first, second and third raw data series, to result respectively in a first, second and third AC data series representing an unmodulated amplitude response, and
applying a computation engine to the first, second and third AC data series, and to the first, second and third DC data series, and determining therefrom a user current blood oxygen saturation level,
wherein the acquiring, at the predefined sampling frequency, of the photoplethysmography light response is performed by (i) a broadband photodiode configured to receive red and infrared light rays, and (ii) a selective photodiode configured to receive green light rays.