Related papers: Picolitre viscometry using optically rotated parti…
We employ multiple sinusoid modulated optical tweezers to measure the frequency dependent rheological parameters of a linear viscoelastic fluid over five decades of frequency in a single shot, hitherto not achieved using active…
The optical trapping and manipulation of small particles is an important tool for probing fluid properties at the microscale. In particular, microrheology exploits the manipulation and rotation of micron-scale particles to probe local…
We report a novel technique capable of measuring the kinematic shear viscosity of Newtonian liquids with steady streaming in microfluidic devices. This probe-free microrheological method utilizes sub-kilohertz liquid oscillation frequencies…
Currently, optical- or mechanical-resonances are commonly used in microfluidic research. However, optomechanical oscillations by light pressure were not shown with liquids. This is because replacing the surrounding air with water inherently…
We present a falling-sphere viscometer with a magnetized sphere and fluxgate magnetometers continuously measuring the magnetic field produced at the sensor positions by the falling sphere. With a fluid volume of 15 ml and within a few…
A method to measure the viscosity of liquids at microscales is presented. It uses a thin glass fiber fixed on the tip of the cantilever of an extremely low noise Atomic Force Microscope (AFM), which accurately measures the cantilever…
When electrons flow as a viscous fluid in anisotropic metals, the reduced symmetry can lead to exotic viscosity tensors with many additional, nonstandard components. We present a viscometry technique that can, in principle, measure the…
Viscosity is an important property of out-of-equilibrium systems such as active biological materials and driven non-Newtonian fluids, and for fields ranging from biomaterials to geology, energy technologies and medicine. However,…
We present an optomechanical device platform for characterization of optical, thermal, and rheological properties of fluids on the micron scale. A suspended silicon microdisk resonator with a vibrating mass of 100 fg and an effective…
We simulate macroscopic shear experiments in active nematics and compare them with microrheology simulations where a spherical probe particle is dragged through an active fluid. In both cases we define an effective viscosity: in the case of…
The experimental literature on the motion of mesoscopic probe particles through polymer solutions is systematically reviewed. The primary focus is the study of diffusive motion of small probe particles. Comparison is made with measurements…
Calibration of optically trapped particles in-vivo has been complicated given the frequency dependence and spatial inhomogeneity of the cytoplasmic viscosity, and the requirement of accurate knowledge of the medium refractive index.…
The motion of submerged magnetic microspheres rolling at a glass-water interface has been studied using magnetic rotation and optical tweezers combined with bright-field microscopy particle tracking techniques. Individual microspheres of…
Considering the nonlinear response of non-Newtonian fluids to the local shear exerted on the bulks of fluid, the initially quasi-uniform distribution of the particles might be subject to alteration as well, due to the unbalanced force…
It is shown that the oscillation method to study liquid viscosity of [1-3,7-34] is based on incorrect consideration of one dimensional forced (constrained) )vibrations of plate in viscous liquid, because additional (apparent) mass of liquid…
We present an experimental procedure to perform broadband microrheological measurements with optical tweezers. A generalised Langevin equation is adopted to relate the time-dependent trajectory of a particle in an imposed flow to the…
Optical tweezers are a technique in which microscopic-sized particles, including living cells and bacteria, can be non-intrusively trapped with high accuracy solely using focused light. The technique has therefore become a powerful tool in…
Many processes in microfluidics and biology are driven or affected by viscosity. While several methods are able to measure this parameter globally, very few can provide high resolution viscosity images. Optimizing the locality of viscosity…
We report for the first time the theory of optical tweezers of spherical dielectric particles embedded in a chiral medium. We develop a partial-wave (Mie) expansion to calculate the optical force acting on a dielectric microsphere…
We use active microrheology to determine the frequency dependent moduli of a linear viscoelastic fluid in terms of the polymer time constant ($\lambda$), and the polymer ($\mu_p$) and solvent viscosity ($\mu_s$), respectively. We measure…