How a phone's accelerometer works - a terrific video

[Video Link]Excellent video by Bill Hammock that looks at the accelerometer in a mobile phone, and how it's made.

Bill takes apart a smartphone and explains how its accelerometer works. He also shares the essential idea underlying the MEMS production of these devices.This video is based on a chapter from the EngineerGuy team's latest book Eight Amazing Engineering Stories.

(Via Cult of Mac)


  1. Very cool explanation.

    As a geologist and a long-time cellphone holdout, I decided it was time to get one when accelerometers were built in. Now I can digitally measure the orientation of geologic structures, take a picture of the outcrop, and everything is geotagged to boot. Amazing. Way, way more important to me than being able to produce random fart sounds or battle birds.

    1. I’m also a geologist but I haven’t measured any outcrops since getting a smartphone. I too had the same thought immediately when I first played with a device with an accelerometer, since Bruntons are so ridiculously expensive. But I’m curious, do you trust the smartphone readings enough to forgo the Brunton? Have you taken measurements with both to double-check?

  2. Thanks, Mark. Feel slightly less dumb. Now – someone tell me what an iPhone screen does in zero gravity.

    1. It rotates when you move it fast enough.

      But taking it into space (or any other zero gravity environment) would probably void your warranty ;)

    2.  I’d guess that it just keeps its last orientation – it’s in ‘freefall’, so it probably won’t measure whatever percentage of 1g in any direction that it takes to trigger a screen rotation.

    3. This reminds me of that time when the office techs were talking about the new G4 (MAC) and I thought they were talking about the G4 (Gulfstream). So yeah, thanks from the non-techies too.

    4.  Zero gravity doesn’t mean zero acceleration.  If you swing your hand in an arc, it will presumably interpret “away” as “down”. (The are also apps that respond to non-gravity acceleration, such as shaking the phone.)

  3. I have no issues with the jargon  in this presentation. In case anyone wondered . . . 

  4. OK, this explanation makes sense for an accelerometer that works on a single axis.  Since the silicon chip is flat, I can also imagine having a second one oriented at 90 degrees, covering the X and Y axis (with respect to the phone).  But how the HEQUE do they put one on the Z-axis using the process he described?  I’m still pretty convinced of magic here.

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