How does an accelerometer work on an iPhone?

How does an accelerometer work on an iPhone?

It's done with nanotechnology now. A "weight" at the end of a springy stick(s) moves when things accelerate, sensors measure how much it moves. But it's all on a chip. At least 3 accelerometers are needed for x, y, z axes, or 2 if some axes are combined.

See microphotograph of such a "silicon accelerator" integrated with a chip used in smartphones:

image

The "weight" is actually that floating corner piece, connected to the main body on both sides by long folded-up "springy sticks". See how it works? Trace out the cuts in this structure. I think the sensor is at that "dimple" at the very corner.