Motion of nanometer sized magnetic particles in a magnetic field gradient
Artikel i vetenskaplig tidskrift, 2008

Using magnetic particles with sizes in the nanometer range in biomedical magnetic separation has gained much interest recently due to their higher surface area to particle volume and lower sedimentation rates. In this paper, we report our both theoretical and experimental investigation of the motion of magnetic particles in a magnetic field gradient with particle sizes from 425 nm down to 50 nm. In the experimental measurements, we monitor the absorbance change of the sample volume as the particle concentration varies over time. We also implement a Brownian dynamics algorithm to investigate the influence of particle interactions during the separation and compare it to the experimental results for validation. The simulation agrees well with the measurements for particle sizes around 425 nm. Some discrepancies remain for smaller particle sizes, which may indicate that additional factors also influence the separation for the smaller size range. We observe that the separation process includes the formation of chainlike particle aggregates due to the magnetic dipole-dipole interactions between particles when subjected to an external magnetic field. We can also see that the hydrodynamic interaction between these chains contributes to reducing the separation time. In conclusion, we show that the formation of these particle aggregates, and to a less extent the hydrodynamic interactions between them contributes to significantly enhancing the particle separation process. © 2008 American Institute of Physics.

rod-like chains

on-chip

simulations

nanoparticles

ferrofluids

friction coefficient

separation

biomedicine

low reynolds-numbers

suspensions

Författare

Vincent Schaller

Chalmers, Mikroteknologi och nanovetenskap (MC2), Elektronikmaterial och system

Ulli Kraeling

Imego AB - The Institute of Micro and Nanotechnology

Cristina Rusu

Imego AB - The Institute of Micro and Nanotechnology

K. Petersson

Imego AB - The Institute of Micro and Nanotechnology

Jan Wipenmyr

Imego AB - The Institute of Micro and Nanotechnology

A. Krozer

Imego AB - The Institute of Micro and Nanotechnology

Göran Wahnström

Chalmers, Teknisk fysik, Material- och ytteori

Anke Sanz-Velasco

Chalmers, Mikroteknologi och nanovetenskap (MC2), Elektronikmaterial och system

Peter Enoksson

Chalmers, Mikroteknologi och nanovetenskap (MC2), Elektronikmaterial och system

Christer Johansson

Imego AB - The Institute of Micro and Nanotechnology

Journal of Applied Physics

0021-8979 (ISSN) 1089-7550 (eISSN)

Vol. 104 9 no:093918-

Ämneskategorier

Annan teknik

DOI

10.1063/1.3009686