Investigation of drift phenomena in closed-loop capacitive micro accelerometers

The drift phenomena of closed-loop capacitive silicon-based micro accelerometers have been hindering their application in the area of precise and rapid industrial positioning, which especially requires a good dynamic performance. Using both theoretical methods and experiments, this paper will systematically investigate the underlying mechanisms of such phenomena. The possible causes of drift, including thermal effects, dynamic response, capacitor charging and dielectric charging, as described in current literature, were evaluated by specific tests. As a result, the first three factors were ruled out as the cause of drift, by both theoretical derivation and experimental observation, and only dielectric charging was identified as the most plausible contributor to the drift. The movement of charges in SiO(x)on electrodes and glass substrates forms an additional electrostatic field that disturbs the system balance and results in the variation of accelerometer output. The materials analysis and shielding tests carried out demonstrated that the drift phenomena of more than 60% of the tested accelerometers can be explained by the charging effect of dielectric materials, while the remaining sensors require further tests and more complicated models to determine the causes of this drift. The conclusions presented in this paper provide meaningful guidance for improving accelerometer performance in order to meet the demands of high accuracy industrial applications.