Université de Fribourg

Differential dynamic microscopy microrheology of soft materials: A tracking-free determination of the frequency-dependent loss and storage moduli

Edera, Paolo ; Bergamini, Davide ; Trappe, Véronique ; Giavazzi, Fabio ; Cerbino, Roberto

In: Physical Review Materials, 2017, vol. 1, no. 7, p. 073804

Particle-tracking microrheology (PT-μr) exploits the thermal motion of embedded particles to probe the local mechanical properties of soft materials. Despite its appealing conceptual simplicity, PT-μr requires calibration procedures and operating assumptions that constitute a practical barrier to its wider application. Here we demonstrate differential dynamic microscopy microrheology...

Université de Fribourg

Viscoelasticity of nematic liquid crystals at a glance

Giavazzi, Fabio ; Crotti, Stefano ; Speciale, Antonio ; Serra, Francesca ; Zanchetta, Giuliano ; Trappe, Véronique ; Buscaglia, Marco ; Bellini, Tommaso ; Cerbino, Roberto

In: Soft Matter, 2014, vol. 10, no. 22, p. 3938–3949

Polarised microscopy is shown to be a powerful alternative to light scattering for the determination of the viscoelasticity of aligned nematic liquid crystals. We perform experiments in a wide range of temperatures by using an adapted version of the recently introduced differential dynamic microscopy technique, which enables us to extract scattering information directly from the microscope...

Université de Fribourg

Scattering information obtained by optical microscopy: Differential dynamic microscopy and beyond

Giavazzi, Fabio ; Brogioli, Doriano ; Trappe, Véronique ; Bellini, Tommaso ; Cerbino, Roberto

In: Physical Review E, 2009, vol. 80, no. 3, p. 031403

We describe the use of a bright-field microscope for dynamic light scattering experiments on weakly scattering samples. The method is based on collecting a time sequence of microscope images and analyzing them in the Fourier space to extract the characteristic time constants as a function of the scattering wave vector. We derive a theoretical model for microscope imaging that accounts for (a) the...