Breakdown voltage behaviour of electrostatic microactuators

Apparatus designed and built in-house has been used to study the breakdown voltage for different electrode configurations and for wobble micromotor surfaces at separations of less than 100 micrometres. The wobble micromotors studied have a diameter of 4 mm with a height of 200 micrometres and have been designed at Heriot-Watt University and manufactured using the UV-LIGA process. Results are presented for the breakdown voltage between the segments of the micromotor and also between the inner stator, outer stator and bearing. Results are also presented for the breakdown voltage between metallic flat circular and spherical electrodes having diameters of 10 and 20 mm. It is observed that the electrode area and the electrode configuration are important parameters, which affect the value of the breakdown voltage. Reducing the electrode area was found to increase the breakdown voltage. The spherical electrode configuration was found to increase the breakdown voltage, while a rod configuration, analogous to the segments of the micromotor, reduces the breakdown voltage. The breakdown voltage between the stator segments and the bearing was found to be lower than the expected theoretical value based on the separation of these surfaces.