High School High School Engineering TSS

Silicon, Gravity, and Smartphones

What causes phone screens to rotate via detection of movement?

Since I was a child, I recognized that some phones and other devices could detect movement and change their screen’s orientation, but it surprises me that I never asked myself what allows them to do that. For those readers who ponder similar questions or just want some material for future dinner-table conversations, here is a quick overview of a rather amusing and humble piece of technology, the accelerometer.

In simple terms, an accelerometer is a chip-like piece found in the inside of a phone or similar devices (as seen in the video) [B]. And what makes it special is it’s ability to convert mechanical information into electrical information. Thanks to the accelerometer’s micro electro-mechanic system ( a.k.a MEMS), gravity is used to tell phones how to orient themselves. A piece of silicon inside the system reacts to changes of velocity and movement, and this movement is then captured by little brush-like pieces that convert movement into electrical information and transmit it to the phone’s hard drive [A].

Now, a brief session of somewhat fun facts. Accelerometers also allow phones to work as compasses, and they are capable of detecting and measuring earthquakes. MEMS is also used in personal computers to prevent major damage in cases of sudden drops. Finally, prosthetic limbs and other medical appliance may benefit from the application of this sensitive pieces of innovation [C].

One might be used to the idea that we take technology for granted; however, as much as it may be true at times and important to be conscious of, it is always a good thing to learn about those little things we take for granted. As one could see, such a trivial little piece of silicon, metals, and other materials is pivotal for our use of many appliances (it is indeed vital for some of our habits and practices); and it is fascinating to think about the possible uses scientist and innovators may give to it (or take inspiration from it).

As always, the sources and some interesting content is in the reference section below (from there you may also keep diving into the depths of remotely useful information you can find in the internet).


[A] Afrotechmods. “How an accelerometer works.” Dec 23, 2014. Youtube.

[B] EngineerGuy. “How a Smartphone Knows Up from Down (accelerometer).” May 22, 2012. Youtube.

[C] Goodrich, Ryan. “Accelerometers: What They Are & How They Work.” October 1, 2013. LiveScience.


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