Rotational magnetic particles microrheology: the Maxwellian case.
An experimental method based on the rotational dynamics of a magnetic probe is reported to measure the local viscoelasticity of soft materials on microscopic scales. The technique is based on the alignment of dipolar chains of submicrometer magnetic particles in the direction of an applied magnetic field. On one hand, light scattering is used to detect the chains' oscillations over a 0.001-100 Hz frequency range when submitted to an oscillating magnetic field and leads to global microrheological measurements. On the other hand, the chains' rotation toward a permanent magnetic field is observed with a microscope, allowing a local determination of viscoelastic properties on the scale of the chains of particles. We demonstrate the accuracy of both assays with a micellar Maxwellian solution and validate theoretical predictions.
Wilhelm
C
C
Fédération de Recherche, FR2438 Matière et Systèmes Complexes and Laboratoire des Milieux Désordonnés et Hétérogènes, Université Paris 6, Case 78, 4 Place Jussieu, 75252 Paris Cedex 05, France.
Browaeys
J
J
Ponton
A
A
Bacri
J-C
JC