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...

Electrokinetic instability refers to unstable electric field-driven disturbance to fluid flows, which can be harnessed to promote mixing for various electrokinetic microfluidic applications. This work presents a combined numerical and experimental study of electrokinetic ferrofluid/water co-flows in microchannels of various depths. Instability waves are observed at the ferrofluid and water inte...

Based on the momentum and continuity equations for ferrofluid under an applied magnetic field, assuming linear behavior for the magnetic material of the ferrofluid, and using carrying current concentric finite wire magnetic field model, the magnetic force was calculated. A modified Reynolds equation is obtained. It is simultaneously solved with the energy equation numerically by the finite diff...

We report flow instabilities with simultaneous, in-plane-rotating and dc-axial uniform magnetic fields. In uniform dc-axial magnetic fields, a ferrofluid drop in a Hele-Shaw cell with an ,1.0-mm gap forms the familiar labyrinth pattern. With subsequent application of an ,100-G rms in-plane, 20–40-Hz rotating uniform magnetic field, smooth spirals form. If the rotating magnetic field is applied ...

The present study is carried out to investigate the magneto-viscous effects on incompressible ferrofluid flow over a porous rotating disc with suction or injection on the surface of the disc subjected to a magnetic field. The flow under consideration is axi-symmetric steady ferrofluid flow of electrically non-conducting fluid. Karman’s transformation is used to convert the governing boundary la...

A microfluidic pump is described that uses magnetic actuation to push fluid through a microchannel. Operation relies on the use of magnetically-actuated plugs of ferrofluid, a suspension of nanosize ferromagnetic particles. The ferrofluid contacts but is immiscible with the pumped fluid. The prototype circular design demonstrates continuous pumping by regenerating a translating ferrofluidic plu...