This paper presents three dimensional study of a ferrofluid seal, its centering effect and its static capacity. Thus, a method based on a potential energy criterion has been put forward to study the seal shape. But such a use of ferrofluid seals is interesting only if the magnetic field created by the permanent magnets saturates totally the ferrofluid. Two cylindrical structures consisting of t...

We present an electromagnetic linear vibration energy harvester with an array of rectangular permanent magnets as a springless proof mass. Instead of supporting the magnet assembly with spring element, ferrofluid has been used as a lubricating material. When external vibration is applied laterally to the harvester, magnet assembly slides back and forth on the channel with reduced friction and w...

Analyses and measurements have shown anomalous behavior of ferrofluids in alternating and rotating magnetic fields, including flow reversals and negative magnetoviscosities as a function of magnetic field amplitude and frequency. These experiments measure the ferrofluid viscous torque on a rotating cylinder while varying the magnetic field amplitude and frequency, thereby confirming the strong ...

Any single permanent or electro magnet will always attract a magnetic fluid. For this reason it is difficult to precisely position and manipulate ferrofluid at a distance from magnets. We develop and experimentally demonstrate optimal (minimum electrical power) 2-dimensional manipulation of a single droplet of ferrofluid by feedback control of 4 external electromagnets. The control algorithm we...

A suspension of non-magnetic entities in a ferrofluid is referred to as an inverse ferrofluid. Current research to trap non-magnetic entities in an inverse ferrofluid focuses on using large permanent magnets to generate high magnetic field gradients, which seriously limits Lab-on-a-Chip applications. On the other hand, in this work, trapping of non-magnetic entities, e.g., bacteria in a uniform...

Magnetic minerals are mostly identified by a combination of rock magnetic and microscopic techniques and the ferrofluid method in combination with an optical microscope was applied during the last decades. But today, scanning electron microscopy (SEM) is preferred for the observation of mineral phases because its depth of focus and resolving capability at the same magnification. In this study, ...

The purpose of this research is to provide data from ferrofluid flow and torque measurements in uniform and nonuniform rotating magnetic fields that can be compared to theoretical analyses in order to fully understand observed paradoxical ferrofluid behavior. In the presence of rotating magnetic fields, ferrofluid particles will rotate to try to align their magnetic moment with the field but be...

An on-chip transformer with a ferrofluid magnetic core has been developed and tested. The transformer consists of solenoid-type coil and a magnetic core of ferrofluid, with the former fabricated by MEMS technology and the latter by a chemical co-precipitation method. The performance of the MEMS transformer with a ferrofluid magnetic core was measured and simulated with frequencies ranging from ...

Super paramagnetic particles is a new class of magnetic materials that exhibit a susceptibility g near the value of one while most of natural paramagnetic materials have a magnetic susceptibility at least five orders of magnitude lower. Ferrofluid emulsion is one of such systems. A collection of iron oxide nanopanicles (in our case Fe304 with a radius of 6nm) dispersed When the volume fraction ...

The article aimed to analytically investigate the thermophysical behaviors of a ferrofluid in a vertical rectangle with the variation of intensity of the magnetic field, viscosity of the ferrofluid and boundary conditions. The governing equations of the ferrofluid include the continuity, momentum and energy equations for describing the thermal-fluidic behaviors of the ferrofluid and the Maxwell...