Relation between frequency and electrostatic formed by parallel capacitors is analyzed by characteristics of laterally librating beam

and resonant micro accelerometer based on electrostatic stiffness is design by using this relation.The inertial force on mass block caused by external acceleration induces the movement of moving plate of capacitor

resulting a shift of gap changes the resonant frequency of beam

so the acceleration can by measured by measuring the shift of frequency.The operating principle of accelerometer indicates that the mechanical stiffness is constant during sensing

and only related to the change of gap

which decreases the dependence on the mechanical error and residual stress of beam.Analysis indicates accelerometer’s natural frequency is 23.94 kHz under electrostatic stiffness

sensitivity is 20 Hz/g n

which is coincident with the theoretical value 21.17 Hz/g n.