Periodic Reporting for period 1 - MicACol (Microrheology of two-dimensional active colloidal crystals and glasses)
Berichtszeitraum: 2017-09-04 bis 2019-09-03
We first designed and characterized active colloids that are capable of swimming at the fluid-fluid interface. We used catalytic colloids that self-propel due to the decomposition of hydrogen peroxide across a Platinum cap. Later, we verified that such microswimmers can exhibit long-ranged repulsion when they interact with other particles that are also confided in the interfacial plane. In particular, suitable interactions are found when the active particles are orientated such that the Platinum cap and the uncoated hemisphere are wetted by the water sub-phase and the oil upper phase, respectively. We studied the dynamics (i.e. the active trajectories) of these particles inside a crystalline monolayer and focused our attention on one rheological property: the ability of active colloids to leave their equilibrium lattice positions. A direct comparison with colloids manipulated by an optical trap revealed that self-propelling colloids behave in a crystal as if they were driven by an effective force proportional to their free swimming velocity.