A micro-fluxgate sensor based on the Matteucci effect of amorphous magnetic fibers

Abstract The design, construction and performance of a novel micro-fluxgate sensor is presented in this work. The sensor is based on the large Matteucci effect that is observed in amorphous fibers of typical stoicheiometry Fe77.5Si7.5B15 after proper annealing. The sensor requires a single planar coil to function, which was constructed with conventional printed-circuit techniques along with the sensor signal conditioning circuitry. A new signal extraction technique was applied that is superior to the conventional second-order-harmonic concept, as far as sensitivity and signal-to-noise ratio are concerned. A conventional fiber, with diameter 125 μm and a glass-covered fiber, with core diameter 20 μm and glass-cover thickness 20 μm, were used as magnetic cores in the fluxgate sensor. The amorphous fibers were mounted, subsequently, above a planar coil by soldering each two ends without any further mechanical treatment, like bending or twisting. Current annealing was performed before mounting, for both magnetic core types in order to optimize the inductive response of the fibers. The sensor sensitivity, before amplification, was measured to be 74000 V/T. The low magnetic noise observed allows for a relatively high overall precision, which in the case of glass-covered fiber has been verified to be 60 nT; this figure may easily improve by known signal conditioning techniques. The overall sensor head dimensions are 60 mm ×30  mm. Further scaling down may be achieved by means of advanced lithographic techniques in the case of glass-covered amorphous fibers only, which exhibit significant Matteucci effect in lengths down to 5 mm.

[1]  Shoji Kawahito,et al.  A 2D CMOS microfluxgate sensor system for digital detection of weak magnetic fields , 1999 .

[2]  E. Hill,et al.  The limit of fluxgate sensitivity due to Barkhausen noise for single layer and bi-layer permalloy thin film cores , 1995 .

[3]  T. Sagara,et al.  Magnetoresistive Sensors , 1993, IEEE Translation Journal on Magnetics in Japan.

[4]  L. V. Panina,et al.  Magneto-impedance in multilayer films , 2000 .

[5]  Radivoje Popovic,et al.  A new compact 2D planar fluxgate sensor with amorphous metal core , 2000 .

[6]  Pavel Ripka,et al.  AC-driven AMR and GMR magnetoresistors , 1999 .

[7]  E. Belloy,et al.  A new hybrid technology for planar microtransformer fabrication , 1998 .

[8]  A. Zhukov,et al.  Giant magnetoimpedance effect in soft magnetic wires for sensor applications , 1997 .

[9]  Shoji Kawahito,et al.  A fluxgate magnetic sensor with micro-solenoids and electroplated permalloy cores , 1994 .

[10]  R. Jahne,et al.  A miniaturized magnetic-field sensor system consisting of a planar fluxgate sensor and a CMOS readout circuitry , 1996 .

[11]  Radivoje Popovic,et al.  The future of magnetic sensors , 1996 .

[12]  Chong H. Ahn,et al.  A micro-fluxgate magnetic sensor using micromachined planar solenoid coils 1 Paper presented as part , 1999 .

[13]  Fritz Primdahl,et al.  Transverse field effect in fluxgate sensors , 1997 .

[14]  M. Vázquez,et al.  Switching mechanism and domain structure of bistable amorphous wires , 1992, 1992. Digests of Intermag. International Magnetics Conference.

[15]  Paul Horowitz,et al.  The Art of Electronics - 2nd Edition , 1989 .

[16]  E. Belloy,et al.  Development of a Novel Printed Circuit Board Technology for Inductive Device Applications , 1999 .

[17]  H. Hauser,et al.  High-performance magnetoresistive sensors , 2000 .

[18]  A. Hernando,et al.  Magnetic bistability of amorphous wires and sensor applications , 1994 .

[19]  Radivoje Popovic,et al.  CMOS planar 2D micro-fluxgate sensor , 2000 .

[20]  Binasch,et al.  Enhanced magnetoresistance in layered magnetic structures with antiferromagnetic interlayer exchange. , 1989, Physical review. B, Condensed matter.

[21]  Pavel Ripka,et al.  Review of fluxgate sensors , 1992 .

[22]  J Clarke,et al.  The Impact of High-Temperature Superconductivity on SQUID Magnetometers , 1988, Science.

[23]  Pavel Ripka,et al.  Crossfield effect at fluxgate , 2000 .

[24]  Klaus-Peter Jungmann,et al.  A high precision magnetometer based on pulsed NMR , 1996 .

[25]  E. Gerdau,et al.  PURE NUCLEAR BRAGG REFLECTION OF A PERIODIC 56FE/57FE MULTILAYER , 1999 .

[26]  N. Smith,et al.  Very high sensitivity GMR spin-valve magnetometer , 1997 .

[27]  K.-H. Jäckel,et al.  A new optically pumped tandem magnetometer: principles and experiences , 1999 .

[28]  Maria Neagu,et al.  Inverse Wiedemann Effect in glass-covered amorphous wires , 2000 .

[29]  Pavel Ripka,et al.  New directions in fluxgate sensors , 2000 .

[30]  J. N. Avaritsiotis,et al.  Boosting the performance of miniature fluxgates with novel signal extraction techniques , 2001 .

[31]  L. Panina,et al.  Magneto-impedance in Co-based amorphous wires and circular domain dynamics , 2000 .

[32]  Detlef Kunze,et al.  Planar fluxgate sensors: experimental data and theoretical analysis , 1997 .