A Single-axis Electrostatically Driven Weak Magnetic Field Measurement Sensor

Abstract

The invention provides a uniaxially electrostatic-driven sensor for weak magnetic field measurement. The sensor comprises an insulating substrate, a pair of electrostatic driving electrodes, two pairs of input and output electrodes, a giant magnetoresistive (GMR) sensitive element, two same magnetic line collectors, a micro-cantilever, and a modulated film. The insulating substrate is plated withan electrode and a shallow groove is etched on the insulating substrate. The GMR sensitive element and the two magnetic line collectors are fixed on the surface of the insulating substrate as well asthe central axises of the GMR sensitive element and the two magnetic line collectors are formed into a straight line. The micro-cantilever employs a conductive silicon chip for manufacture and comprises a pedestal and a cantilever, wherein the pedestal is fixed on the insulating substrate and is connected with the cantilever and the modulated film is prepared on a lower surface of an upwarp end of the cantilever. A vertical distance from the modulated film to the GMR sensitive element is 8 to 15 micrometers. According to the sensor for weak magnetic field measurement provided in the invention, a modulation depth is great; a resolution is high; and the structure and the technology of the sensor are simple.

Description

technical field [0001] The invention relates to the technical field of sensors, in particular to sensors for weak signals, and in particular to a single-axis magnetic sensor for measuring weak magnetic fields. Background technique [0002] Weak magnetic field measurement is widely used in geomagnetic navigation, target detection, geological exploration, biomedicine and other fields. At present, there are many types of sensors used for weak magnetic field measurement, mainly including fluxgate sensors, optical pump magnetic sensors, proton magnetic sensors, optical fiber magnetic sensors, giant magnetoresistive magnetic sensors, and GMR (Giant Magnetoresistive, giant magnetoresistance) Magnetic sensors, etc. Among them, the GMR magnetic sensor is made based on microelectronics technology. Compared with other types of magnetic sensors, it has the characteristics of small size, low power consumption, and easy mass production. [0003] In 1988, the experimental groups led by th...

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Problems solved by technology

Although this type of technical solution can effectively suppress the 1 / f noise of GMR sensitive elements and significantly improve the low-frequency magnetic field resolution of GMR magnetic sensors, its structure is relatively complicated, and the manufacturing process involves deep reactive ion etching technology and insulating silicon technology. The process is time-consuming and laborious, and the cost is high. In addition, the modulation depth is also low (about 14%), which is not conducive to further improving the magnetic field resolution.

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