Description: Non-local fluctuation correlations in active gels

This title appears in the Scientific Report : 2010

Non-local fluctuation correlations in active gels

Many active materials and biological systems are driven far from equilibrium by embedded agents that spontaneously generate forces and distort the surrounding material. Probing and characterizing these athermal fluctuations are essential to understand the properties and behaviors of such systems. He...

Personal Name(s):	Head, D.A.
	Mizuno, D.
Contributing Institute:	Theorie der Weichen Materie und Biophysik; IFF-2 Theorie der Weichen Materie und Biophysik; IAS-2
Published in:	Physical Review E Physical review / E, 81 81 (2010 2010) 4 4, S. 041910 041910
Imprint:	College Park, Md. APS 2010 2010-04-13 2010-04-01
Physical Description:	041910
DOI:	10.1103/PhysRevE.81.041910
Document Type:	Journal Article
Research Program:	BioSoft: Makromolekulare Systeme und biologische Informationsverarbeitung
Series Title:	Physical Review E 81
Subject (ZB):	J
Link:	OpenAccess OpenAccess
	Publikationsportal JuSER

Please use the identifier: http://dx.doi.org/10.1103/PhysRevE.81.041910 in citations.
Please use the identifier: http://hdl.handle.net/2128/9316 in citations.

Many active materials and biological systems are driven far from equilibrium by embedded agents that spontaneously generate forces and distort the surrounding material. Probing and characterizing these athermal fluctuations are essential to understand the properties and behaviors of such systems. Here we present a mathematical procedure to estimate the local action of force-generating agents from the observed fluctuating displacement fields. The active agents are modeled as oriented force dipoles or isotropic compression foci, and the matrix on which they act is assumed to be either a compressible elastic continuum or a coupled network-solvent system. Correlations at a single point and between points separated by an arbitrary distance are obtained, giving a total of three independent fluctuation modes that can be tested with microrheology experiments. Since oriented dipoles and isotropic compression foci give different contributions to these fluctuation modes, ratiometric analysis allows us characterize the force generators. We also predict and experimentally find a high-frequency ballistic regime, arising from individual force-generating events in the form of the slow buildup of stress followed by rapid but finite decay. Finally, we provide a quantitative statistical model to estimate the mean filament tension from these athermal fluctuations, which leads to stiffening of active networks.