MEMS Electric Field Sensor with Biased Electrically Floating Cover to Measure Electric Field in Ionic Environments

Electric field measurement is widely applied in HVDC area. However, it is a challenge to measure dc electric field in ionic environment using a packaged sensor. When the sensor is packaged in an enclosure, the landing of charge particles from environment on the enclosure surface would give an off-setting electric field, and so cause measurement error. In this paper we propose a method to bias an electrically floating metal cover above the packaged sensor, to prevent ions landing on the package cover, while still being able to measure electric field external to the enclosure. Experimental results show that when the floating cover is pre-biased, ionic charge accumulation can be reduced and eliminated. The sensor sensitivity remains at 70 mV(kV/m)
^-1
, with and without ionic charge present in the environment.