Transport Of Magnetic Particles Research Articles

Controlled transport of magnetic particles using soft magnetic patterns

Inspired by magnetic bubble memory technology, we demonstrate the temporal and spatial manipulation of superparamagnetic beads guided by soft magnetic patterns in a rotating magnetic field. Soft magnetic structures allow complex and repetitive tasks to be performed. As a demonstration, we show cyclic capture and release of antibodies from different microfluidic streams.

Enhanced magnetic particle transport by integration of a magnetic flux guide: Experimental verification of simulated behavior

In the past, magnetic biosensors have shown to be promising alternatives for classical fluorescence-based microarrays, replacing the fluorescent label by a superparamagnetic particle. While on-chip detection of magnetic particles is firmly established, research groups continue to explore the unique ability of manipulating these particles by applying controlled magnetic forces. One of the challenging tasks in designing magnetic force generating structures remains the generation of large forces for a minimal current consumption. Previously, a simple transporting device for single magnetic particles has been demonstrated using a magnetic field that is generated by two tapered current carrying conductors [R. Wirix-Speetjens, W. Fyen, K. Xu, J. De Boeck, and G. Borghs, IEEE Trans. Magn. 41(10), 4128 (2005)]. We also developed a model to accurately predict the motion of a magnetic particle moving in the vicinity of a solid wall. Using this model, we now present a technique that enhances the magnetic force up to a factor of 3 using a magnetic flux guide. The larger magnetic force results in an average speed of the particle which increases with a factor of 3. These simulations show good agreement with experimental results.

A force study of on-chip magnetic particle transport based on tapered conductors

Recently, magnetic biosensors have shown to be promising alternatives for classical fluorescence-based detection schemes. While on-chip detection of magnetic particles is well established, research groups now start to explore the unique possibility to manipulate these particles by applying controlled magnetic forces. By immobilizing biomolecules onto the particle's surface, this results in a number of additional functionalities, turning the label-which was previously solely a means of detection-into a "smart" label. In this paper, we give an overview of the dominant forces acting on a magnetic particle when manipulated by transporting devices such as the ones that are currently developed at our lab. First, we describe a computational approach to predict the motion of the magnetic particle. It is based on a force balance of perpendicular forces to determine the particle/substrate separation distance. After this, we calculate the in-plane forces that determine the mobility of the particle and which are dependent on this separation distance. Next, we validate this model for the movement of particles in water. We then show how the surface forces influence the particle/substrate separation distance-and therefore the mobility of the particle-for various pH values and ionic strengths of the liquid.

On-Chip Magnetic Particle Transport by Alternating Magnetic Field Gradients

We have demonstrated an on-chip magnetic bead transport device based on a set of two tapered current conductors. We have fabricated and tested two types of devices. Both devices are capable of trapping single magnetic microbeads and guiding them along a defined magnetic track. We examined scaling of the basic repetitive element and found good agreement among experiment, theory, and simulations. This novel magnetic transport mechanism opens possibilities for controlled manipulation of magnetically labeled biomolecules.

The characteristics of mass transfer processes in magnetic fluids

Theoretical study shows that in magnetic fluids a new phenomenon - thermomagnetophoresis should take place. In accordance with experiment made in a vertical column in a transverse uniform magnetic field, there occurs magnetic particle transport along the heat flow. The experimental data on the thermomagnetophoretic rate are in relatively good agreement with the results of the theoretical investigation.