Helium in the air kills iOS devices? (MEMS oscillator vulnerability)

[cdev]

Why do sealed plastic bags sometimes expand with trapped gases inside over time?

[DenzilPenberthy]

Why do sealed plastic bags sometimes expand with trapped gases inside over time?

Maybe due to atmospheric pressure decreasing over that time period, or changing temperature?

[TheSteve]

A friend of mine has had his Apple watch replaced twice due to helium exposure.

edit - I should add that he does work around helium at times, the sensors are very sensitive.

[StillTrying]

"This is around half a pascal with normal air, due to its 5 ppm helium content. An increase of helium concentration beyond 5 ppm in the surrounding air will also lead to a corresponding increase in the internal helium pressure."

I know helium is strange, but I still find this MEMS problem hard to believe!

[Red Squirrel]

I bet everyone in that room was talking pretty funny too.   

[StillTrying]

Why do sealed plastic bags sometimes expand with trapped gases inside over time?

Fumes from the plastic itself ?

[BrianHG]

Tested true here:


I bet they are just driving that crystal too weakly, or just at the edge of it's tuning capacitance.

[ChunkyPastaSauce]

[ruffy91]

Tested true here:


I bet they are just driving that crystal too weakly, or just at the edge of it's tuning capacitance.

MEMS oscillators do not use quartz crystal which is piezoelectric. They use polysilicon in a electric field. They are much worse than quartz (25ppm/K temperature dependency). But there is 1 big advantage. You can make them very small and you can make them out of the same silicon as the rest of an IC, they are much smaller even including drive circuitry and temperature compensation than a quartz.
I think Apple devices are more affected because they use MEMS oscillators for all devices while most Android devices still use quartz.