Magnetic Torque of Microfabricated Elements and Magnetotactic Bacteria
We present a thorough theoretical analysis of the magnetic torque on microfabricated elements with dimensions in the range of 100 to 500 {\mu}m and magneto-somes of magnetotactic bacteria of a few {\mu}m length. We derive simple equations for field dependent torque and magnetic shape anisotropy that...
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Main Authors | , , , , , |
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Format | Journal Article |
Language | English |
Published |
07.08.2014
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Subjects | |
Online Access | Get full text |
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Summary: | We present a thorough theoretical analysis of the magnetic torque on
microfabricated elements with dimensions in the range of 100 to 500 {\mu}m and
magneto-somes of magnetotactic bacteria of a few {\mu}m length. We derive
simple equations for field dependent torque and magnetic shape anisotropy that
can be readily used to replace the crude approximations commonly used. We
illustrate and verify the theory on microfabricated elements and magnetotactic
bacteria, by field depedent torque magnetometry and by observing their rotation
in water under application of a rotating magnetic field. The maximum rotation
frequency of the largest microfabricated elements agrees within error
boundaries with theory. For smaller, and especially thinner, elements the
measured frequencies are a factor of three to four too low. We suspect this is
caused by incomplete saturation of the magnetisation in the elements, which is
not incorporated in our model. The maximum rotation frequency of magnetotactic
bacteria agrees with our model within error margins, which are however quite
big due to the large spread in bacteria morphology. The model presented
provides a solid basis for the analysis of experiments with magnetic objects in
liquid, which is for instance the case in the field of medical microrobotics. |
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DOI: | 10.48550/arxiv.1408.1570 |