2014 We have observed the surface instability of the interface between a highly concentrated ferrofluid and a weakly concentrated one. Our experimental data clearly show the first order character of the transition between a flat interface and the observed regular pattern of peaks. A large hysteresis effect is observed because of the high value of the relative permeability (03BC ~ 40) of our con...

The viscosity n of Fe,O, ferrofluid at volume concentrations in the range t = 0.0-0.013 are measured. The corresponding range of values of q is 1.6-1.8 cp. A linear relationship exists between the relative viscosity and the concentration of the fluid. Measurements of relative resistivity of Fe,O, ferrofluid at various concentrations (E = 0.00526-0.0526) are also reported. The relative resistivi...

A novel micromixer which utilizes chaotic mixing induced by ferrofluid actuation is developed. The micromixer is fabricated by a polydimethylsiloxane micromolding technique. The micromixer consists of a T-shaped main mixing channel and two parallel sub-channels that intersect the main channel. Oscillation of a couple of ferrofluid slugs in the sub-channels, induced by external permanent magnet ...

We present a new method for the determination of the magnetic moment distribution ρ(μ) of ferrofluid particles from the magnetization curve measured on diluted ferrofluid samples in the liquid state. The method employs the solution of the standard integral equation describing the magnetization of a non-interacting particle system in the given external field as a convolution of the Langevin func...

Magnetic manipulation is a promising technique for lab-on-a-chip platforms. The magnetic approach can avoid problems associated with heat, surface charge, ionic concentration and pH level. The present paper investigates the migration of diamagnetic particles in a ferrofluid core stream that is sandwiched between two diamagnetic streams in a uniform magnetic field. The three-layer flow is expand...

A simple, cost effective and sensitive fiber optic magnetic sensor fabricated with ferrofluid and commercially available fiber optic components is described in this paper. The system uses a ferrofluid infiltrated extrinsic Fabry-Perot interferometer (EFPI) interrogated with an infrared wavelength spectrometer to measure magnetic flux density. The entire sensing system was developed with commerc...

Concerns dealing with the application of superparamagnetic ferrofluid as a drug carrier are studied both experimentally and theoretically. A dynamically controlled electromagnet experiment was designed to focus a stable ferrofluid trap at a specified distance. A theoretical magnetic driving force equation has been compared to experimental results for verification; verification was not achieved....

The influence of a magnetic field on the dynamics of the flow of a ferrofluid in the gap between two concentric, independently rotating cylinders is investigated numerically. The Navier-Stokes equations are solved using a hybrid finite difference and Galerkin method. We show that the frequently used assumption that the internal magnetic field within a ferrofluid is equal to the external applied...