Abstract
We present an extension of the two-point optical microrheology technique introduced by Crocker et al. [ J. C. Crocker, M. T. Valentine, E. R. Weeks, T. Gisler, P. D. Kaplan, A. G. Yodh and D. A. Weitz, Phys. Rev. Lett., 2000, 85, 888 (ref. 7)] to high frequencies. The correlated fluctuations of two probe spheres held by a pair of optical tweezers within a viscoelastic medium are determined using optical interferometry. A theoretical model is developed to yield the frequency-dependent one- and two-particle response functions from the correlated motion. We demonstrate the validity of this method by determining the one- and two-particle correlations in a semi-dilute solution of polystyrene in decalin. We find that the ratio of the one- and two-particle response functions is anomalous which we interpret as evidence for a slip boundary condition caused by depletion of polymer from the surface of the particle.
Original language | English |
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Pages (from-to) | 323-334 |
Number of pages | 12 |
Journal | Faraday Discussions |
Volume | 123 |
DOIs | |
Publication status | Published - Jan 2003 |
Bibliographical note
[it 43 citations]Keywords
- MICROSCOPIC VISCOELASTICITY TRACKING MICRORHEOLOGY THERMAL FLUCTUATIONS COMPLEX FLUIDS SOFT MATERIALS PARTICLE MODULI
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