Microrheology of complex fluids using optical tweezers pdf

Microrheology of a sticking transition nature physics. Nonlinear microrheology of an aging, yield stress fluid. It is a new way of doing rheology, traditionally done using a rheometer. In this paper we discuss the basic idea of microrheology and we will focus on one specific technique based on optical tweezers ot. Optical tweezers 1 use a highly focused laser beam to form a stable trap to confine. In particular, in the case of passive microrheology with optical tweezers mot, where.

While most microrheology techniques belong to either one of passive or active families, ot are the only such systems where an external force is always active onto the probe particle, whatever be the chosen modus operandi, hence its hybrid nature. Such measurements require the knowledge of absolute displacements of the trapped particles. Optical forces are commonly exerted by using microscopebased optical tweezers to trap and move the tracers. Microrheology of complex fluids using optical tweezers iopscience.

Unlike passive microrheology methods, which use diffusing microspheres to extract rheological properties, optical tweezers can probe the nonlinear viscoelastic response, and measure the space and. Since their first appearance in the 1970s, optical tweezers have been successfully exploited for a variety of applications throughout the natural sciences, revolutionising the field of microsensing. Ouyang, forces on a colloidal particle in a polymer solution. Combined with fast and high sensitive position detection techniques, they are suitable for microrheological measurements of viscous and viscoelastic media. Microrheology is a branch of rheology having the same principles as conventional bulk rheology, but working on micron length scales and microlitre volumes. Optical tweezers have been successfully adopted as exceptionally sensitive transducers for microrheology studies of complex fluids.

Pdf microrheology is the study of the flow of materials over small scales. Despite the general trend, in this article i explain why a similar approach should not be adopted for microrheology studies of. Passive and active microrheology with optical tweezers. For instance, the pioneering work of chu and coworkers introduced singlepolymer visualization and manipulation to understand polymer dynamics in dilute and entangled solutions of dna 9, 10.

Optical forces provide a contactless and precise way to manipulate microbeads suspended in a fluid. Microrheology using dualbeam optical tweezers and ultrasensitive force measurements microrheology using dualbeam optical tweezers and ultrasensitive force measurements knoener, gregor g. Small amplitude active oscillatory microrheology of a. It then explores in greater detail the use of optical tweezers as an emerging method to investigate. Optical tweezers have become a powerful tool to explore the viscoelasticity of complex fluids at micrometric scale.

Linear microrheology with optical tweezers of living cells. The use of optical forces for particle manipulation, sorting, and analysis alexandr jonas. Optical tweezers have been successfully used with newtonian fluids for rheological purposes such as determining fluid viscosity. Laser tweezer microrheology laser tweezer microrheology is performed by measuring the displacement of colloidal probes x as they are held in an optical trap and subjected to a uniform. Applications of laser tweezers in complex fluid rheology. Unlike passive microrheology methods, which use di. It is of particular interest to those involved with investigations of fluid. Conversely, when optical tweezers are used to measure the viscoelastic properties of complex fluids the results are either limited to the materials highfrequency response, discarding important.

We then use either highly sensitive drag force measurements or video tracking to map the fluid velocity around that particle. The phenomenon of sticking of one object to another, which drastically reduces their relative motion, is ubiquitous in nature. Spatiallyresolved rotational microrheology with an. New experimental techniques to extend these probe measurements and new methods for data interpretation have been developed. We present a fast active microrheology technique exploring the phase response of a microscopic probe particle trapped in a linear viscoelastic fluid using optical tweezers under an external perturbation. Optical tweezers are especially useful for applications in complex fluids when combined with realspace imaging, such as video and confocal microscopy. Microrheology with optical tweezers lab on a chip rsc. Mason t g, ganesan k, van zanten j h, wirtz d and kuo s c 1997 particle tracking microrheology of complex fluids phys. Schematic of optical trap with components needed for microrheology experiments. Our results are compared to a new theoretical model that explicitly accounts for different bath and probe particle sizes and the three independent contributions to the stress.

Mason tg 2000 estimating the viscoelastic moduli of complex fluids using the generalized stokeseinstein equation. Tracer microrheology in complex fluids sciencedirect. In a context of microrheology of complex bioinspired fluids, we use this tool here to study if the lack of statistics may influence the observed potential of a bead trapped by optical tweezers. Optical tweezers as a tool for microrheology of simplex. In particular, the solutions were prepared with gxm exopolysaccharide isolated from in vitro culture of seven clinical c.

Left a schematic representation of an optically trapped bead within a harmonic potential er, where. Opticaltweezersbased microrheology of soft materials and living. Integrated microfluidic viscometer equipped with fluid temperature controller for measurement of viscosity in complex fluids. Osa optical tweezers based active microrheology of. The local viscoelasticity was compared between fulllength and telopeptideremoved collagen solutions using optical tweezers based microrheology. Bonales and others published microrheology of complex fluids find, read and cite all the research you need on researchgate. This procedure allows us to measure the material linear viscoelastic properties across the widest frequency range. We used oscillatory optical tweezers to investigate the microrheological properties of sodium polystyrene sulfonate napss. In the case of microrheology with ot of complex fluids, tassieri et al. Conversely, when optical tweezers are used to measure the viscoelastic properties of complex fluids. Microrheology of complex fluids using optical tweezers. Optical tweezers offer a powerful platform for performing microrheology measurements and can measure rheological properties at the level of single molecules out to near macroscopic scales. Tracer microrheology in complex fluids thomas gisler and david a weitzt recent results suggest that the motion of colloidal particles can be interpreted in terms of the viscoelasticity of the surrounding medium. Using optical tweezers, we have measured the relative viscosities of purified gxms dissolved in ultrapure water, at concentrations ranging from 0.

Microrheology is a technique used to measure the rheological properties of a medium, such as microviscosity, via the measurement of the trajectory of a flow tracer a micrometresized particle. Over the past few decades, microrheology has emerged as a widely used technique to measure the mechanical properties of soft viscoelastic materials. Probing telopeptideinduced collagencollagen interactions. This is achieved by following a linear path that starts from a narrative introduction of the nature of light. Despite the general trend, in this article i explain why a similar approach should not be adopted for microrheology studies of living cells. Thus, we experimentally determine the cumulative response of the probe to an entire repertoire of sinusoidal excitations simultaneously by applying a spatial square pulse as an. An optical method established for complex liquids and dna solutions is particle tracking microrheology. Microrheology is a rheological method that uses colloidal tracer particles, dispersed within a sample, as probes. Microrheology of complex fluids institute of physics. When performed on living cells or in vitro reconstituted biomaterials, this technique is termed bio microrheology. The discussion starts from newtonian fluids to tackle the more general case of complex fluids, also showing results of these techniques on solutions of a relevant biomolecule. Further, we report the first use of magnetic tweezers to.

Mw 70kda polymer solutions with different concentrations from 0. The setup is characterized in terms of the accessible stresses, the applied magnetic fields, and the measurable viscosities and shear rates. The output results of bdl are directly compatible with the format used by standard microrheological algorithms 4. Measuring storage and loss moduli using optical tweezers. Optical tweezers have become a widely used tool for manipulate microscopic objects.

Integrated optofluidic chip for oscillatory microrheology. A generalised langevin equation is used to relate the frequencydependent moduli of the complex fluid to the. However, when adopted for microrheology studies, there exist some peaks and troughs on their modus operandi and data analysis that i wish to address and possibly iron out, providing a guide to. We present an experimental procedure to perform broadband microrheological measurements with optical tweezers. In the experiments, the brownian trajectories of optically confined microparticles are properly analysed to provide the viscous and elastic moduli g. Blinking optical tweezers for microrheology measurements of weak elasticity complex fluids.

The mechanical properties of cells are crucial for cell sensing and reaction to mechanical environments. We create flow vortices by rotation of birefringent particles in optical tweezers. Published 20 january 2009 iop publishing ltd journal of optics a. Conversely, when optical tweezers are used to measure the viscoelastic properties of complex fluids the results are either limited to the. It covers experiments of four groups of biological systems arranged by increasing complexity. Our on the fly calibration in time domain has been used to probe microscopic structural changes in the complex fluid. A generalised langevin equation is adopted to relate the timedependent trajectory of a particle in an imposed flow to the frequencydependent moduli of the complex fluid. Microrheology of complex fluids iopscience institute of physics. We measure the microviscosity of a colloidal suspension using active, oscillatory laser tweezer microrheology. Recent citations nanofluidic behavior at the fluid solid interface yan chen et al. Passive and active microrheology with optical tweezers r r brau, j m ferrer, h lee et al. An enhanced modulus at higher concentrations in fulllength collagen solutions suggests contributions from telopeptideassociated transient crosslinks. In order to better appreciate the microrheological methods with optical tweezers explored in this book, informative introductions to the basic concepts of linear rheology, statistical mechanics, and the most popular microrheology techniques are also given. Measuring the relative viscosity of solutions at a glance.