Institut Fresnel

Principal investigator: Pierre Sabouroux

Keywords: complex permittivity, complex permeability, coaxial line

Understanding wave-matter interactions demands the most accurate knowledge of the intrinsic properties of matter, namely the dielectric complex permittivity and magnetic complex permeability. In the high frequency metrology domain, measurement devices of these quantities are practically non-existent nowadays.
Therefore, we developed and propose a technological solution to determine these properties in any sort of material: solids, liquids and semi-solids (granular materials, powder, gels…). This technique can be used in association with the monitoring of other physical properties, such as temperature, water content, pressure, etc...

The application domains are multiple. For example, our measurement setup allows exploring the variation domain of the dielectric constant of biologic media such as blood and/or sugar content in biological liquids. An adapted temperature monitoring system allowed testing the response of these liquids when the temperature increases or decreases.

Additionally, in High Field MRI, dielectric pads have been used to perform passive shimming between the RF antennas and the imaging area on the patient. To optimize these dielectric pads, we have characterized the optimum material with our experimental setup. Furthermore, to test the response of these dielectric pads in a MRI scan of a human head, we completed this study with the manufacture of an anthropomorphic head phantom having the major characteristics necessary to simulate the SAR distribution and the relaxation effects in the brain. All materials, having a gel consistency, are measured with the innovative setup developed in the laboratory.

Likewise, with this new system we were able to study a few exotic materials at very low temperature, such as porous ices and mixtures with organic powders (regolith analog or Tholins) for astronomy research programs in collaboration with the Physics Institute in Bern (Switzerland).

On the domain of the construction industry, in collaboration with EDF and Andra, we applied our technique to monitor the dielectric permittivity versus water content to know the ageing of technical concretes or sand using in nuclear reactors.

As a final example, we use our measurement technique to evaluate the permittivity of essential oils for a laboratory specialized in its extraction through microwave assisted extraction devices.

Nowadays, the technological solutions developed in this domain are the center of numerous patents (www.epsimu.com) and industrial advancement by way of operating license agreements (www.ccrm.fr).

Recent publications
E. Georget, R. Abdeddaim, P. Sabourouxl
Aquasi-universal method tomeasure the electromagnetic characteristics of usual materials in the microwave range, C. R. Physique 15 (2014) 448–457, http://dx.doi.org/10.1016/j.crhy.2014.02.003

Y. Brouet, A.C. Levasseur-Regourd, P. Sabouroux, L. Neves, P. Encrenaz, O. Poch, A. Pommerol, N. Thomas, W. Kofman, A. Le Gall, V. Ciarletti A. Hérique, and A. Lethuillier
A porosity gradient in 67P/C-G nucleus suggested from CONSERT and SESAME-PP results: an interpretation based on new laboratory permittivity measurements of porous icy analogues.
MNRAS Advance Access published September 5, 2016

Y. Brouet, L. Neves, P. Sabouroux, A. C. Levasseur-Regourd, O. Poch, P. Encrenaz, A.Pommerol, N. Thomas, W. Kofman
Characterization of the permittivity of controlled porous water ice/dust mixtures to support the radar exploration of icy bodies
JGR-Planets, accepted November 2016, in press