Particle-tracking microrheology (PT-mu r) exploits the thermal motion of embedded particles to probe the local mechanical properties of soft materials. Despite its appealing conceptual simplicity, PT-mu r requires calibration procedures and operating assumptions that constitute a practical barrier to its wider application. Here we demonstrate differential dynamic microscopy microrheology (DDM-mu r), a tracking-free approach based on the multiscale, temporal correlation study of the image intensity fluctuations that are observed in microscopy experiments as a consequence of the translational and rotational motion of the tracers. We show that the mechanical moduli of an arbitrary sample are determined correctly over a wide frequency range provided that the standard DDM analysis is reinforced with an iterative, self-consistent procedure that fully exploits the multiscale information made available by DDM. Our approach to DDM-mu r does not require any prior calibration, is in agreement with both traditional rheology and diffusing wave spectroscopy microrheology, and works in conditions where PT-mu r fails, providing thus an operationally simple, calibration-free probe of soft materials.

Differential dynamic microscopy microrheology of soft materials: A tracking-free determination of the frequency-dependent loss and storage moduli / P. Edera, D. Bergamini, V. Trappe, F. Giavazzi, R. Cerbino. - In: PHYSICAL REVIEW MATERIALS. - ISSN 2475-9953. - 1:7(2017 Dec 29), pp. 073804.1-073804.11.

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

Edera, Paolo;Giavazzi, Fabio;Cerbino, Roberto
2017-12-29

Abstract

Particle-tracking microrheology (PT-mu r) exploits the thermal motion of embedded particles to probe the local mechanical properties of soft materials. Despite its appealing conceptual simplicity, PT-mu r requires calibration procedures and operating assumptions that constitute a practical barrier to its wider application. Here we demonstrate differential dynamic microscopy microrheology (DDM-mu r), a tracking-free approach based on the multiscale, temporal correlation study of the image intensity fluctuations that are observed in microscopy experiments as a consequence of the translational and rotational motion of the tracers. We show that the mechanical moduli of an arbitrary sample are determined correctly over a wide frequency range provided that the standard DDM analysis is reinforced with an iterative, self-consistent procedure that fully exploits the multiscale information made available by DDM. Our approach to DDM-mu r does not require any prior calibration, is in agreement with both traditional rheology and diffusing wave spectroscopy microrheology, and works in conditions where PT-mu r fails, providing thus an operationally simple, calibration-free probe of soft materials.
Complex fluids; particle tracking; colloidal dynamics; light-scattering; diffusion; gels; viscosity; water
Settore FIS/07 - Fisica Applicata(Beni Culturali, Ambientali, Biol.e Medicin)
Settore FIS/03 - Fisica della Materia
Anisotropies and non equilibrium in soft matter: routes to the self assembly of advanced materials
Light for Life
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/2434/572848
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