Watch How iPhone Accelerometers Work and Are Made

Every modern smartphone can change the orientation of the display based on the phone’s rotation thanks to its accelerometer. The technology behind the accelerometer is fascinating, if only because the chip is so small.

The video describing the accelerometer comes from Bill Hammack, The Engineer Guy. In the video, Hammack takes apart an old iPhone 3G (or maybe 3GS) and shows us the tiny gravity-sensing chip inside.

Traditional accelerometers use a “seismic mass” attached to a spring encased in some sort of housing. As the device moves the mass moves on the spring and the device can measure the movement. Using multiple units a device can determine which way the it turned based on which masses move.

The iPhone and other smartphones use a different method, however. Modern smartphones instead use a small silicon chip with a springy center that moves with gravity. Creating the chip is more difficult than creating the traditional accelerometer. The process involves putting masks over the silicon then dripping corrosive potassium hydroxide over it.

According to Cult of Mac, the end result is a small chip that costs Apple just 65 cents apiece. It’s hard to believe that such a complicated process that human hands can’t even do is so inexpensive.

No matter the price, the technology behind such a tiny chip that most users take for granted is quite interesting. It makes us wonder how complicated other small parts in smartphones are, like the gyroscopes.