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[Preprint]. 2021 Feb 18:2021.02.17.21249755. [Version 1] doi: 10.1101/2021.02.17.21249755

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Figure 1: — (A) shows the location of the SpO₂ sensor on the back of the smartphone making clear that the sensor is entirely separate from the other phone devices such as the camera. In the expanded view (B) the dedicated photo sensor and LEDs for the pulse oximetry function are shown. The device has a total of 4 LEDs two of which are reserved for future additional functionality. The arrow indicates the 660 nM red and 910nM infrared LEDs used in this measurement. The photodetector is connected to an extremely low noise analog channel allowing measurement on a broad range of skin colors.