Patent ID: 11937923
Assignee: WITHINGS
Field: Medical technology (Instruments)
Classification: CPC A | IPC A

Claim 0:
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.