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Développement d'un magnétomètre optique pour la cardiographie foetale

English title Development of an optical magnetometer for fetal cardiography
Applicant Weis Antoine
Number 113641
Funding scheme Project funding
Research institution Département de Physique Université de Fribourg
Institution of higher education University of Fribourg - FR
Main discipline Technical Physics
Start/End 01.10.2006 - 30.09.2007
Approved amount 131'110.00
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All Disciplines (2)

Discipline
Technical Physics
Cardiovascular Research

Keywords (7)

magnetocardiography (MCG); fetal magnetocardiography (FMCG); biomagnetism; optical magnetometry; fetal magnetocardiograph; optical magnetometer; gradiometer

Lay Summary (English)

Lead
Lay summary
We propose to develop an optical magnetometer for recording the time varying magnetic fields generated by the fetal heart (optical fetal magnetocardiograph, OFMCG). Combined laser spectroscopy and magnetic resonance in cesium vapor cells will be used. Recording fetal MCGs is very challenging because the maximal field amplitudes are 10-20 times weaker than those from adult hearts. At present, only a handfull of SQUID installations in the world can work at the required sensitivity. The prohibitive cost of SQUID technology, due to the use of cryogenics, is a major obstacle to its widespread application. Optical magnetometers have lower capital cost and negligible operating cost.
While working with our adult MCG maps, the noise on the recorded data was limited by imperfect cancellation of the ambient fluctuating magnetic fields (magnetic noise), and thus the intrinsic sensitivity (<100 fT/Hz½) of our sensor was never the limitation. We will improve the intrinsic sensor sensitivity to the required level of 10 fT/Hz½ and then the primary experimental effort will be to improve the noise suppression by the use of higher order gradiometers. Noise suppression which leaves us limited only by the intrinsic sensitivity will allow us to detect the fields generated by the fetal heart. Sensor distribution geometry will be optimized for the fetal field detection. The research will be conducted in a magnetically shielded room available in Fribourg.
The results of the noise suppression and sensitivity improvement will be integrated into a second stage device which will conform to the geometry constraints imposed by the fetal monitoring problem. This mainly consists of reducing the size of the field suppression coils and placing them very close to the sensor cells. All tests with the system at this stage will be done with signals generated by coils, similar to the previous development phase, with the goal of achieving a highly reliable system.
After the device has been successfully tested in the geometry necessary for fetal measurements, the third stage of testing will be with volunteers in a hospital setting to evaluate and analyze a normal fetal cardiac rhythm. The results will be compared to those obtained by fetal M-mode echocardiography.
With such a functional device, fetal arrhythmias, such as fetal heart block and tachycardia, can be diagnosed allowing timely therapeutic intervention. In addition, fetal myocardial ischeamia might be detectable and will allow a better management of such a distressed fetus. Reliable and affordable optical fetal magnetocardiography will therefore have an unprecedented impact on the management of high risk pregnancies.
Direct link to Lay Summary Last update: 21.02.2013

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