Why not just pull the battery,then hold the power button down to release any residual electricity, then pull the screen and clean the phone with some Electrical contact cleaner,or parts cleaner(something that will not leave any residue behind). You might want to use a soft,small artists paint brush.
I bought a zippered semi hard camera case for when I had to work around Acid,sulfates,hazardous chemicals,and working outside for long periods of time.
I don't use it all the time,just when I need to. My phone still looks and acts great.