"Manipulation of long-term dynamics in a colloidal active matter system using speckle light fields"

March 17, 2016

Manipulation of long-term dynamics in a colloidal active matter system
using speckle light fields

Erçağ Pinçe
Bilkent University, Ankara, Turkey


Particles undergoing a stochastic motion within a disordered medium is a ubiquitous physical
and biological phenomena. Examples can be given from organelles performing tasks in the
cytoplasm to large animals moving in patchy environment. Here, we use speckle light fields
to study the anomalous diffusion in an active matter system consisting of micron-sized silica
particles (diameter 5μm) and motile bacterial cells (E. coli). The speckle light fields are generated
by mode mixing inside a multimode optical fiber where a small amount of incident laser power
is needed to obtain an effective disordered optical landscape for the purpose of optical manipulation.
We experimentally show how complex potentials contribute to the long-term dynamics of the active
matter system and observed an enhanced diffusion of particles interacting with the active bacterial
bath in the speckle light fields. We showed that this effect can be tuned and controlled by varying
the intensity and the statistical properties of the speckle pattern. Potentially, these results could be
of interest for many technological applications, such as the manipulation of microparticles inside
optically disordered media of biological interest.

Date: March 17, 2016 (Thursday)
Time: 9:36 -9:48
Place: APS March Meeting 2016, Baltimore, Maryland, USA