Advances in the microrheology of complex fluids

Abstract

New developments in the microrheology of complex fluids are considered. Firstly the requirements for a simple modern particle tracking microrheology experiment are introduced, the error analysis methods associated with it and the mathematical techniques required to calculate the linear viscoelasticity. Progress in microrheology instrumentation is then described with respect to detectors, light sources, colloidal probes, magnetic tweezers, optical tweezers, diffusing wave spectroscopy, optical coherence tomography, fluorescence correlation spectroscopy, elastic- and quasi-elastic scattering techniques, 3D tracking, single molecule methods, modern microscopy methods and microfluidics. New theoretical techniques are also reviewed such as Bayesian analysis, oversampling, inversion techniques, alternative statistical tools for tracks (angular correlations, first passage probabilities, the kurtosis, motor protein step segmentation etc), issues in micro/macro rheological agreement and two particle methodologies. Applications where microrheology has begun to make some impact are also considered including semi-flexible polymers, gels, microorganism biofilms, intracellular methods, high frequency viscoelasticity, comb polymers, active motile fluids, blood clots, colloids, granular materials, polymers, liquid crystals and foods. Two large emergent areas of microrheology, non-linear microrheology and surface microrheology are also discussed.

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

“…Microrheology is a very powerful complement to traditional, mechanical rheology [5,[7][8][9]. For the high-frequency range, rheology is usefully complemented by DWS-μr [10], whereas in the low-frequency limit both DLS-μr [11] and PT-μr [6] have been usefully employed in the past.…”

“…A complementary approach that addresses the above issues is represented by microrheology [5][6][7][8][9]. Originally introduced by Mason and Weitz in 1995 [10], the so-called passive microrheology consists of seeding the soft material of interest with tracer particles of radius a and measuring the mean-square displacement (MSD) r 2 (t) of the tracers within the material as a function of time t. If the material is homogeneous on the length scale of the tracers size, the MSD of noninteracting tracers can be related to the frequency-dependent complex modulus G * (ω) by using the generalized Stokes-Einstein relation (GSER) [7] G * (ω) = dk B T 3πas r 2 (s) s=iω ,…”

Particle manipulations in non-Newtonian microfluidics: A review

“…HA is found in many biological systems such as synovial fluids in joints for the prevention of high-load impacts [50]. DNA solution is strongly viscoelastic because of the long relaxation time of DNA molecules [54].…”

High Resolution Measurements of Viscoelastic Properties of Complex Biological Systems Using Rotating Optical Tweezers

“…In contrast microrheology studies fluids on microscopic scales. Besides this, microrheological approaches offer a series of advantages over bulk techniques [125]. Bulk rheometers provide an average measurement of the bulk response; they do not allow for local measurements of inhomogeneous materials which are sensitive to the length scale.…”

“…The microrheological technique is able to access a much wider frequency interval. Microrheology has become a much better established field in both theory and experiment that is able to treat much smaller sample volumes, has an improved frequency sensitivity, provides delicate non-invasive measurements and has an improved sensitivity to intracellular dynamics [25,31,108,125,133,138].…”