Bellows are differential pressure sensing devices mainly
used in low pressure ranges of about 0 to 1000 pascals.
Here we show a set of metallic bellows, held inside a
protective casing. The bellows are made of a thin copper
alloy tube pressed into a corrugated shape. This is
sealed at one end, with a small hole at the other end.
When pressure is applied via the hole, the bellows
expand a distance d. This displacement can be calibrated