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Nonlinear Rotation of a Magnetic Microsphere with Attached Bacterium

Coming Soon:

Simulation of Linear ("synchronous") Rotation

Simulation of Nonlinear ("asynchronous") Rotation



bulletNonlinear Rotation

Magnetic nonlinear micro-oscillators are an emerging detection method that has been shown to detect single bacteria in fluid – see Figure. The technique is based on a magnetic microsphere’s nonlinear rotational response to an external driving magnetic field, i.e. the microsphere rotates out-of-synch with the external magnetic field (see videos to the left). Magnetic microspheres are latex spheres with incorporated magnetic materials, such that they can be rotated in magnetic fields. Their rotation rate can be easily monitored with a low magnification microscope interfaced to a CCD camera. Magnetic nonlinear micro-oscillators can also be used to monitor single bacteria growth dynamics.

Nonlinear Rotation of Magnetic Particles References:


B.H. McNaughton, R.R. Agayan, R. Clarke, R. Kopelman, Single bacterial cell detection with nonlinear rotation rate shifts of driven magnetic microspheres, Applied Physics Letters, 91 (2007).

B.H. McNaughton and R. Kopelman, Nonlinear rotation rate shifts of driven particles and uses thereof, Patent Pending (2007).

B.H. McNaughton, R.R. Agayan, J.X. Wang, R. Kopelman,
Physiochemical microparticle sensors based on non-linear magnetic
, Sensors and Actuators B 121, 330-340 (2007).

B.H. McNaughton, Karen Kehbein, Jeffrey N. Anker and Raoul
Kopelman, S
udden breakdown in linear response of a rotationally driven magnetic microparticle and application to physical and chemical microsensing, J. Phys. Chem B. 110,18958 (2006).

C.J. Behrend, J.N. Anker,  B.H. McNaughton, R. Kopelman, “Microrheology with modulated optical nanoprobes (MOONs),” Journal of Magnetism and Magnetic Materials 293, 663-670 (2005).








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