I can't remember the source for my information here, but I have read that there are caps that people put over the sensors when not in use. Also, some people put them in plastic bags, removing the air.
The oxygen in the air reacts with the sensor, depleting the oxygen. Eventually, in a sealed environment, there is no more oxygen left to react with the sensor. Maintaining the sensor in this environment will prolongue its life.
I have been using the plastic bag method on a sensor for about a year and a half. So far, so good.
This is not to say that I pull a heavy vacuum on the bag. I just purge out the air when sealing the bag. Perhaps, if you pull a strong vacuum, this could damage the sensor, or it might do nothing. I don't know. You could just play it safe by not pulling such a vacuum but otherwise getting rid of pretty much all air in the sealing environment.
