MEMS... Micro Electro-Mechanical Sy

MEMS... Micro Electro-Mechanical Systems. MEMS are kind of like silicon integrated circuits, but their mechanical in nature,MEMS manufacturers use similar techniques that are used to make electronics, but instead they're making tiny mechanical structures that can interface to electronics, allowing you to build some interesting things. Here I've got some MEMS dies that I made out of silicon. They contain a lot of the same basic structures that you might find in a modern chip. Let's take a look under the microscope. This is a tiny resistor. The lighter colored material is actually electrically conductive silicon. And this darker area that's been edged away doesn't conduct, this long winding electrical path forms a resistor very similar to how a long piece of wire would also have a significant resistance.So if you made an electrical connection between these two points, you'd have a microscopic resistor. Now, in order to understand how an accelerometer works, let's look at a MEMS capacitor. It doesn't look much like a capacitor, does it? Well, remember that all the capacitor, really is, is two conductive plates that are electrically separated. Here are the two terminals of the capacitor. Over here, we have what's called a comb finger arrangement, the two structures are very close to each other, but they aren't quite touching. Let me highlight it for you.Now, it should be more obvious that you have parallel surfaces which form a capacitor. But this is no ordinary capacitor. It's a physical structure that can move. This thing over here is basically a tiny weight made out of silicon. And it's kind of like a suspended mass on the end of a spring .Movement , vibrations and even gravity can cause this little mass to move around. And when it does, it shifts the entire combed finger structure. When the fingers move, the distance between the fingers changes. And when the distance between the fingers changes, you get a change in capacitance. So now we have an electro mechanical system that can sense movement and turn it into a changing capacitance value. The next step would be to design circuitry that can sense the change in capacitance and convert it into useful voltages or serial data. But that's beyond the scope of this tutorial. A modern MEMS accelerometer will contain structure similar to this, except with even more fingers to increase the surface area, which increases the capacitance, which makes changes in acceleration easier to detect. Now, you know how an accelerometer works. Thanks for watching.