A miniaturized RMS voltage sensor based on a torsional actuator in bulk silicon technology

摘要

In this paper, we present an advanced RMS voltage sensor based on a torsional actuator using the principle of electrostatic force. The actuator is built using a micromechanical bulk silicon process yielding structures with a low rotational spring constant due to beams with a high length to width ratio. A metal layer provides separated excitation and sensing electrodes. The actuator is mounted on a matching glass substrate with a shallow rectangular cavity in which the opposite electrodes are located and which defines the working distance to be as low as 15 μm. To prevent stiction, a novel wet etched layer provides small sized bumpers. An innovative electrode arrangement gives six independent capacitances for position sensing or electric excitation. Design choices and the micromechanical process are explained in detail and first DC and RF measurement results are presented.