Modern smartphones are filled to the brim with all kinds of sensors, modules and sensors, each of which performs a different role. And most of them remain invisible to us. We scan our fingerprints voluntarily, but in the case of the proximity or light sensors, we rely solely on automation. We are all the more surprised when we realize that the sensor that used to turn off the screen when you put it to your ear has failed and no longer does what it's supposed to do.