MEMS micro fluxgate sensors with mutual vertical excitation coils and detection coils

Abstract

As a classic Earth magnetic field sensor, fluxgate magnetic sensors have great potential applications in many fields. This paper presents a new 3D micro-solenoid fluxgate magnetic sensor based on the MEMS technique. The excitation coils were placed vertically to the detection coils on the chip plane, around a rectangular shaped magnetic core. Polyimide was used to insulate coils and magnetic core. Width of copper conductor lines is 50 lm, and line space is 50 lm. The design of such fluxgate magnetic sensor followed second harmonic signal selecting method. Phase-lock amplifier was used to get second harmonic signal output by detection coils. The linear range of 0-80 lT with sensitivity of 6.7 V/T was achieved from the fabricated sensor with excitation current of 430 mA and the operational frequency of 40 KHz. As the excitation current was 470 mA, linear range of 0-50 lT with sensitivity of 21.7 V/T was achieved.

Magnetic Field Sensors Based on Microelectromechanical Systems (MEMS) Technology

“…www.intechopen.com Other examples of MEMS-based fluxgate devices have been reported by Chong Lei et al (2009) and Kirchhoff & Büttgenbach (2010).…”

Design, fabrication and testing of sandwich coupled inductors

“…Coupled inductor with planar coil structure has recently emerged as important and popular device in RF-IC for DC-signal isolation, LC filter, amplifier, and impedance matching (Long 2000). In other microelectronics applications, couple inductors play important role as voltage regulator and AC-DC converter (Prabakharan et al 2004;Wang et al 2004) as well as magnetic sensors (Fluxgate magnetometer) (Baschirotto et al 2007;Drljaca et al 2005;Lei et al 2009). …”

Geometrical analysis of planar coil design for fluxgate magnetometer

“…Various models of the coupled coil used for fluxgate magnetometer have been reported, including solenoid type (Park et al 2004), toroid type (Lei et al 2009), stack planar (Ripka et al 2001) and double axial planar coils (Baschirotto et al 2007). Among the various types, single layer planar coil has the advantage of less via connections, which determines successful connection of conductor traces between the layers.…”