THE HUMAN HEART BEAT DETECTED BY CESIUM ATOMS
A. Weis1*, G. Bison1, R. Wynands1,2
1Physics Department, University of Fribourg, Chemin du Musée 3, 1700 Fribourg, Switzerland
2Present address: Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany
* Corresponding author. E-mail:email@example.com
Received : 15 February 2003; revised version accepted : 23 January 2004
Stimulated by recent progress in laser-based optical magnetometry and in developments of powerful signal denoising techniques we initiated the development of a low-cost laser-driven optically pumped magnetometer (OPM) for biomagnetic applications. The OPM uses optically pumped cesium atoms in glass cells of a few cm3. Its sensitivity (<100 fT in 1 Hz bandwidth), bandwidth (45 Hz), and spatial resolution (cm) were optimized in order to allow us the two-dimensional mapping of the magnetic field produced above the chest by the beating human heart. Signal averaging by using an electrocardiographic signal as a reference reduces residual noise significantly and allows one to display the dynamics of the heart field as a movie. We discuss the principle of the technique and give a status report on ongoing work towards the development of a multichannel device.
Keywords: Magnetometry; Laser spectroscopy; Magnetic resonance; Magneto-cardiography; MCG.