Design of a silicon microphone with differential read-out of a sealed double parallel-plate capacitor

A new design of a sealed capacitive microphone with differential capacitive read-out and high sensitivity is presented, The design allows for higher electrical bias fields and thereby higher sensitivities compared to ordinary capacitive microphones. The bias field can be further increased if force balancing is used, which is very simple to implement with this design. To avoid too high bias voltages, the air gap is reduced. The design is based on analytical modelling and finite-element calculations.