Abstract
The present invention relates to a device, system and method for determining the concentration of a substance, such as the oxygen saturation, in the blood of a subject, which reduce or remove the influence of specular reflection and/or subject motion. The proposed device comprises an input unit (11) for receiving detection signals reflected back or transmitted through a skin area of the subject in response to irradiation of the skin area by a radiation signal, a signal extraction unit (12) for extracting at least three photo-plethysmography, PPG, signals at different wavelengths from said detection signals, a processing unit (13) for normalizing said at least three PPG signals and forming a first difference signal between a first normalized PPG signal and a second normalized PPG signal and a second difference signal between a third normalized PPG signal and one other of the at least three normalized PPG signals and for forming a ratio between said first difference signal and said second difference signal, and an concentration detection unit (14) for calculating the concentration of a substance in the blood of the subject based on said ratio.
| Original language | English |
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| Patent number | WO2015197383 |
| IPC | A61B 5/ 1455 A I |
| Priority date | 23/06/14 |
| Publication status | Published - 30 Dec 2015 |