EGAS41 - Swansea University

41 st EGAS CP 170 Gdańsk 2009
Laser-driven Cs magnetometer arrays for cardiomagnetic field
imaging
M. Kasprzak 1,∗ , G. Bison 2 , N. Castagna 1 , A. Hofer 1 ,
P. Knowles 1 , J.-L. Schenker 1 , A. Weis 1
1 Department of Physics, University of Fribourg,
Chemin du Musée 3, CH–1700 Fribourg, Switzerland
2 Department of Neurology, Friedrich-Schiller-University,
Erlanger Allee 101, D–07747 Jena, Germany
∗ Corresponding author: malgorzata.kasprzak@unifr.ch
Magnetocardiography is an innovative diagnostic method for cardiac diseases, based on
the measurements of the weak magnetic fields (50–100 pT amplitude) produced by the
electrical activity of a human heart. In current practice, magnetometers based on superconducting
quantum interference devices (SQUIDs), which require cooling to 4 K,
are the sensor of choice. However, due to the high capital investment and maintenance
costs of such devices, there is a need and an interest in alternative methods of heart
field detection. This issue has been investigated by the Fribourg Atomic Physics Group
(FRAP) and resulted in the development of an optical Cs magnetometry system adapted
to the heart measurement problem [1,2]. The magnetometer sensors record the Larmor
precession frequency of Cs atoms in paraffin-coated vapor cells (28 mm diameter) via
the optically detected magnetic resonance technique. A system of 25 Cs magnetometers,
arranged as 19 second-order gradiometers with full digital control electronics has been
built (Fig. 1). It is currently used for magnetic field imagining of healthy subjects and
cardiac patients. This poster will give details on the sensors and their operation in the
multichannel arrangement.
Figure 1: Left: The 19 channel second-order magnetic gradiometer system using 25 mounted
sensors. The lowest plane contains 19 sensors, and the two upper planes contain each three
sensors generating reference signals used to form the second-order gradiometer signal. Right:
Magnetic field map of the artificial heart at the maximum of the R-peak.
Acknowledgment
Work funded by the Swiss National Science Foundation, #200020–119820, and the Velux Foundation.
References
[1] G. Bison, R. Wynands, A. Weis, Optics Express 11, 904 (2003)
[2] G. Bison, R. Wynands, A. Weis, Appl. Phys. B 76, 325 (2003)
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