Buy a pack of screen protectors for your phone. Cut a piece of cardboard or paper to the shape of the logo covering the sensor then use it as a template to cut the screen protectors. Store them in your car. Put one on and when it gets covered with bugs, dirt, etc, peel it off and replace it.
Another option is to use a non-abrasive spray wax on the emblem. I use Meguiars Quik Wax which allows bugs to easily wipe off the surface.
