Understanding MEMS accelerometer

Hi,

I'm trying to figure out how a MEMS accelerometer works by measuring the change in capacitance.

Here is a diagram of a MEMS accelerometer.
memsaccel.png

I edited the picture as shown below with the red area where i think each plate from the movable yellow frame matches with a plate on the fixed white frame. This leaves the two plates in the blue area which are unused. Am i correct? If yes, then why are these plates there? A wild guess would be... to protect the springs?
Another idea would be that the capacitance is being measured between each movable plate and the two fixed plates on each side of it? I'm not sure if/how that would even work.
memsaccel edit.png

memsaccel.png

memsaccel edit.png

Try to understand capacitors. Capacity in above pictures depends on the distance between the white and yellow electrodes. If the yellow electrodes come closer to the white electrodes in horizontal direction, regardless of direction, the capacity increases. Differential capacity change could be observed when the upper and lower white electrodes are separated, and the yellow electrodes move towards the top or bottom of the picture. Then the capacity increases with the amount of overlap with the upper or lower white electrodes, and decreases at the other side.

See variable capacitor.