Sampling 'small atmospheres' in the tiny new worlds of MEMS

Sandia gas sampling device rapidly determines whether MEMS seals are effective

Just as astronomers want to understand the atmospheres of planets and moons, so engineers want atmospheric knowledge of worlds they create that are the size of pinheads, their "skies" capped by tiny glass bubbles.
Should their silicon inhabitants - microcircuits, microgears, and micropower drivers - exist in a vacuum? An atmosphere of nitrogen? Air as we know it? More importantly, whatever atmosphere was intended, how long will it stay that way? Is the protective barrier hermetic or will its atmosphere change over time, potentially leading to the early death of the device? Will water vapor seep in, its sticky molecules causing unpredictable behavior? What, in short, can we say about how long this little world and its inhabitants will survive and function?