Design, fabrication, and calibration of capacitive air gap sensors for the application in levitation based guides in microactuators

The development of a capacitive sensor for controlling the gap of contactless guides in microactuators is presented in this paper. The counter electrode of the capacitive air gap sensor is kept free from electric leads and the dimension of the active region of the sensor is 445 µm × 950 µm. For the fabrication of the sensor, thin-film processes were applied. The capacitance at the upper measurement range of 15 µm represents 125 fF. An appropriate evaluating circuit provides enough resolution to operate at the pre-defined gap of 7 µm.