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Probing collective dynamics of active particles using modulation force spectroscopy

Soni, GV and Ananthakrishna, G and Shivashankar, GV (2004) Probing collective dynamics of active particles using modulation force spectroscopy. In: Applied Physics Letters, 85 (12). 2414 -2416.


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In this letter, we report a method of measuring the dynamic viscosity of self-propelled active particles using an intensity-modulated optical tweezer. We have used a 6 µm trapped polystyrene bead suspended in a bath of motile bacterial cells as a probe. The response function amplitude of the oscillatory bead directly measures the dynamics of the spatiotemporal structure of the motile particles. We find that unlike passive systems, the viscosity is defined by distributions of response function amplitudes that represent the long-range active temporal structures. Appropriate Langevin equations are set up that capture all these essential features.

Item Type: Journal Article
Additional Information: Copyright for this article belongs to American Institute of Physics (AIP).
Department/Centre: Division of Chemical Sciences > Materials Research Centre
Division of Physical & Mathematical Sciences > Physics
Depositing User: L.Kaini Mahemei
Date Deposited: 22 Mar 2005
Last Modified: 19 Sep 2010 04:18
URI: http://eprints.iisc.ac.in/id/eprint/2960

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