Highly sensitive magnetometers—a review

Abstract Conventional magnetic sensors, easy to use, are supposed to work mainly well over the nanotesla range, as due to the large magnetic environmental noise occurring in urban and industrial environments. On the other hand, a strange world exists, well below the nanotesla range, where the very efficient magnetic properties of superconducting materials have been used. It is the world investigated using cryogenic sensors, especially those of the SQUID's family. During a long time starting from the 1960s, SQUID people have refined their technologies, together with the use of advanced signal processing both analogue and digital, in order to input couple various external magnetic sources at room temperature, such the bio magnetic ones. State of the art of SQUID sensors is given. In the early 1990s, the dramatic improvement of the operating temperature led to the hope of lighter and lower costs systems with reduced cryogenic mount, designed to operate in open environment. An important target of multi SQUID systems using high critical temperature superconductors was and still is the magnetocardiography (MCG) mapping that could be daily used for improved diagnosis, as compared to conventional electrocardiography. It is known that such an important application is realistic only with noise spectral densities referred at the input lower than 100 fT/√Hz in a frequency bandwidth lying in between 1 Hz and 1 kHz and with a spatial resolution lower than 1 cm. The talk will review the recent advances in room temperature solid state sensors that could reach the above specified noise level. The review includes: magnetoresistive devices (AMR, GMR, spin valve, and spin dependent tunnelling device), Giant magneto-inductive devices. Non-solid, atomic vapor laser magnetometers, which have recently shown their ability to deliver very clear MCG signals, and start to be used to map the MCG signal above the chest just like SQUIDs systems, are reviewed. A simple, convenient energy resolution—volume is proposed, which allows a convenient way to compare high sensitivity magnetic sensors.

[1]  Robert Wynands,et al.  Optimization and performance of an optical cardiomagnetometer , 2004, physics/0406157.

[2]  Robert Wynands,et al.  A laser-pumped magnetometer for the mapping of human cardiomagnetic fields , 2003 .

[3]  John P. Wikswo.  SQUIDs Remain Best Tools for Measuring Brain’s Magnetic Field , 2004 .

[4]  Dietmar Drung,et al.  High-performance DC SQUID read-out electronics , 2002 .

[5]  H. Koch.  SQUID magnetocardiography: status and perspectives , 2001 .

[6]  K. Müller,et al.  Possible highTc superconductivity in the Ba−La−Cu−O system , 1986 .

[7]  T. W. Kornack,et al.  A subfemtotesla multichannel atomic magnetometer , 2003, Nature.

[8]  Sébastien Saez,et al.  Progress towards the optimization of the signal-to-noise ratio in giant magnetoimpedance sensors , 2006 .

[9]  Dietmar Drung,et al.  High-Tc and low-Tc dc SQUID electronics , 2003 .

[10]  Petr I. Nikitin,et al.  Epitaxial yttrium iron garnet film as an active medium of an even-harmonic magnetic field transducer , 2003 .

[11]  Chi,et al.  Direct measurement of the superconducting properties of single grain boundaries in Y1Ba2Cu3O7- delta. , 1988, Physical review letters.

[12]  Erik Stokstad.  Divining Diet and Disease From DNA , 2000, Science.

[13]  Julia M. Phillips,et al.  Substrate selection for high‐temperature superconducting thin films , 1996 .

[14]  J. Bednorz,et al.  Possible High T c Superconductivity in the BaL a-C u-0 System , 2022 .

[15]  Sébastien Saez,et al.  Signal-to-noise improvement of bio-magnetic signals using a flux-gate probe and real time signal processing , 1998 .

[16]  Shu-Hsien Liao,et al.  High-Tc SQUID gradiometer system for magnetocardiography in an unshielded environment , 2003 .

[17]  W. Gawlik,et al.  Resonant nonlinear magneto-optical effects in atoms , 2002, physics/0203077.

[18]  Claude Fermon,et al.  Femtotesla Magnetic Field Measurement with Magnetoresistive Sensors , 2004, Science.

[19]  A. Boukhenoufa,et al.  High-sensitivity giant magneto-inductive magnetometer characterization implemented with a low-frequency magnetic noise-reduction technique , 2005, IEEE Sensors Journal.

[20]  Sébastien Saez,et al.  Highly sensitive uncooled magnetometers: State of the art. Superconducting magnetic hybrid magnetometers, an alternative to SQUIDs? , 2001 .

[21]  R Wynands,et al.  Dynamical mapping of the human cardiomagnetic field with a room-temperature, laser-optical sensor. , 2003, Optics express.

[22]  O. Kronenwerth,et al.  Low-noise magnetic-flux sensors based on the extraordinary magnetoresistance effect , 2004 .

[23]  Peter M. Vetoshko,et al.  Measuring low alternating magnetic fields by means of Bi‐containing rare‐earth ferrite‐garnet films with planar anisotropy , 1991 .

[24]  Christophe Dolabdjian,et al.  INVESTIGATION IN DETECTION OF FATIGUE CRACKS UNDER RIVET HEAD AIRFRAME USING IMPROVED GMR MAGNETOMETER IN AN EDDY CURRENT SYSTEM , 2004 .

[25]  Claude Fermon,et al.  Ultra-sensitive mixed sensors—Design and performance , 2006 .

[26]  Valeriy V. Yashchuk,et al.  Sensitive Magnetometry based on Nonlinear Magneto-Optical Rotation , 2000 .

[27]  Hines,et al.  Enhanced Room-Temperature Geometric Magnetoresistance in Inhomogeneous Narrow-Gap Semiconductors. , 2000, Science.