Browsing by Author "Staforelli, J. P."

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    Controlling the dynamics of colloidal particles by critical Casimir forces
    (Royal Society of Chemistry, 2019-01) Magazzu, A.; Callegari, Agnese; Staforelli, J. P.; Gambassi, A.; Dietrich, S.; Volpe, Giovanni
    Critical Casimir forces can play an important role for applications in nano-science and nano-technology, owing to their piconewton strength, nanometric action range, fine tunability as a function of temperature, and exquisite dependence on the surface properties of the involved objects. Here, we investigate the effects of critical Casimir forces on the free dynamics of a pair of colloidal particles dispersed in the bulk of a near-critical binary liquid solvent, using blinking optical tweezers. In particular, we measure the time evolution of the distance between the two colloids to determine their relative diffusion and drift velocity. Furthermore, we show how critical Casimir forces change the dynamic properties of this two-colloid system by studying the temperature dependence of the distribution of the so-called first-passage time, i.e., of the time necessary for the particles to reach for the first time a certain separation, starting from an initially assigned one. These data are in good agreement with theoretical results obtained from Monte Carlo simulations and Langevin dynamics.
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    Erratum: controlling the dynamics of colloidal particles by critical Casimir forces (Soft Matter (2019) 15 (2152-2162) DOI: 10.1039/C8SM01376D)
    (Royal Society of Chemistry, 2020) Magazzu, A.; Callegari, Agnese; Staforelli, J. P.; Gambassi, A.; Dietrich, S.; Volpe, Giovanni
    Correction for ‘Controlling the dynamics of colloidal particles by critical Casimir forces’ by Alessandro Magazzù et al., Soft Matter, 2019, 15, 2152–2162, DOI: 10.1039/C8SM01376D. The authors regret an error in the grant number for one of the authors in the Acknowledgements section. The Acknowledgements section should read as follows: This work was partially supported by the ERC Starting Grant ComplexSwimmers (grant no. 677511) and by Vetenskapsrådet (grant no. 2016-03523). A. C. acknowledges partial financial support from TUBITAK (grant no. 116F111). J. P. S. acknowledges partial financial support from FONDECYT (grant no. 1171013). The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers.
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    Spatial measurement of spurious forces with optical tweezers
    (SPIE, 2013) Bordeu, I.; Volpe, Giovanni; Staforelli, J. P.
    The study of diffusion in a crowded and complex environment, such as inside a cell or within a porous medium, is of fundamental importance for science and technology. Combining blinking holographic optical tweezers and sub-pixel video microscopy permits one to study Brownian motion in confined geometries. In this work, in particular, we have studied the Brownian motion of two colloidal particles interacting hydrodynamically with each other. The proximity between the two microspheres induces a space-dependence in the particles diffusion coefficient and, therefore, a spurious drift. We measure this drift and evaluate the magnitude of the spurious force associated with it. We present the optoelectronic tools employed in the experiment and we discuss the experimental results.