The Google Fit app already has a function available that allows you to use the rear camera lens of a mobile phone to monitor both heart rate and respiratory rate. Both iOS and Android mobiles can do it, although the method for each reading is different.
Google announced that the feature would be available in early 2021 , but it was not officially launched until a year later.
To detect the heart rate it will be necessary for the user to place the fingertip on the rear camera lens , while for the monitoring of the respiratory rate the camera will take into account the movements of the chest, so the camera will have to be focused towards that part.
This reading of vital signs is activated from the vital “Explore-Contacts” menu of the Google Fit app, the Google application that centralizes the monitoring of physical and sports activity.
In this menu, the different monitoring options will appear (depending on the compatibility of the smartphone model used): heart rate and respiratory rate. To start measuring them, simply click on the Start label in the required option.
At that time Google Fit will request permission to use the camera, since the measurements are made with this component. In the case of heart rate measurement, Google Fit asks you to remain still (and silent) while placing your finger on the lens for a few seconds.
Regarding the measurement of the heart rate, the front camera is used, and the subject must be located within some boxes marked on the screen corresponding to the face and chest . Google Fit detects movements in both parts, from which it calculates the number of times you breathe per minute.