Development of a noncontact current sensor based on MEMS technology

Abstract

Most ofMEMS sensors are based on the micro-cantilever technology, which use wide range of different design materials and structures. The benefit ofMEMS technology is in developing devices having lower cost, lower power consumption, higher performance, and integration. A free-end cantileverbeam made of magnetic material (PerrnaIloy) and a movable mass attached to the free-end has been designed using MEMS software tools. The magnetic material was used to improve the sensitivity of the cantilever-beam to an external applied magnetic field. The deflection of the cantilever was detected using capacitive sensing method. The aim of this research was to develop a non-contact current sensor based on MEMS technology by analysing the simulation of the system design of the micro cantilever when subjected to a magnetic field produced by a current-carrying conductor. When the signal, a sinusoidal current with a constant frequency is applied, the cantilever-beam exhibits a vibration motion along the vertical axis when it is placed closer to the line current. This creates corresponding capacitance changes and generates a voltage output proportional to the capacitive change in the signal processing circuitry attached to the micro cantilever. Modelling of the magnetic moment of a magnetic cantilever-beam placed in a field, the deflection of { the beam, the natural frequency of the cantilever-beam, the maximum deflection, the change in differential capacitive sensing technique, linearity of the differential capacitive, and capacitive sensitivity the circuit designed for readout was derived.