Controlled torque on superparamagnetic beads for functional biosensors.
Biosens Bioelectron
; 24(7): 1937-41, 2009 Mar 15.
Article
em En
| MEDLINE
| ID: mdl-19022651
ABSTRACT
We demonstrate that a rotating magnetic field can be used to apply a controlled torque on superparamagnetic beads which leads to a tunable bead rotation frequency in fluid. Smooth rotation is obtained for field rotation frequencies many orders of magnitude higher than the bead rotation frequency. A quantitative model is developed, based on results from a comprehensive set of experiments at different field strengths and frequencies. At low frequencies (<10Hz), rotation is due to a small permanent magnetic moment in the bead. At high frequencies (kHz-MHz), the torque results from a phase lag between the applied field and the induced magnetic moment, caused by the non-zero relaxation time of magnetic nanoparticles in the bead. The control of torque and rotation will enable novel functional assays in bead-based biosensors.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Técnicas Biossensoriais
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Separação Imunomagnética
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Sistemas Microeletromecânicos
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Magnetismo
Tipo de estudo:
Diagnostic_studies
/
Prognostic_studies
Idioma:
En
Ano de publicação:
2009
Tipo de documento:
Article