What capacitance change will cause the 3 m/sec² acceleration in two different
capacitive accelerometers:
a) a parallel plate accelerometer
b) a comb-drive accelerometer?
Both accelerometers have the spring constant k=1 N/m, the proof mass m=0.1 mg.
a) For the parallel plate accelerometer: the electrode plates is (100 ?m x 20 ?m),
separation between electrodes is 2 ?m,
k=1N/m
Movable electrode
m=0.1 mg
Fixed electrode
b) For the comb-drive accelerometer: A comb-drive accelerometer has hundred
interdigitated fingers. The fingers are built from 3 ?m thick polysilicon
d=2µm
Fixed
?
w=5µm
I=100?m
Movable