The design process of the comb sensor starts with a shape optimization in CST EMS. Here two different shapes are modeled and compared.
Therefore, by using parameters a true shape optimization of the force can be performed.
Figure 1: Potential and electric field for the rectangular and triangular comb tip
After the calculation of fields the forces can be determined as a postprocessing step. Using appropriate boundary conditions, the single combs are assumed to be part of an infinite array. Due to its special shape the triangular comb tip has a 14% higher attracting force.
Figure 2: Potential for a voltage drop of 12 V at the full comb sensor
The simulation of the full comb was performed with open boundary conditions. The total force for a voltage drop of 12 V is 0.64 µN.
This article has shown that a design of a MEMS comb sensor, including a comparison of different tips, can easily be performed within CST EMS. In the case of the full model, one of CST EMS's mesh topologies was applied since its memory efficiency is a vital feature in being able to simulate such large structures.