Characterisation of a Quadrupol Magnetic Field Configuration with a Lorentz Force Based MOEMS Gradiometer

摘要

This paper reports on a MEMS gradiometer consisting of two independent laterally oscillating masses on a single chip with integrated optical readout. The symmetrical design of the two masses offers high accuracy and low cost by using conventional MEMS batch fabrication technology. The sensing principle is based on laterally displacement of the masses actuated by Lorentz forces which modulates a light flux passing through a stationary mask and the moving mask integrated in the masses. Phase and intensity detected by photodiodes reveals information about the uniformity of an external applied magnetic field, hence, enables the measurement of gradient-, homogeneous-and offset zradient maanetic fields. A quadrupol magnetic field created from four identical neodymium bar magnets had been characterised to demonstrate the sensor's working principle.