Microrheology of a sticking transition

Condensed Matter journal club

Microrheology of a sticking transition

Event details

Abstract

The phenomenon of sticking of one object to another, which drastically reduces their relative motion, is ubiquitous in nature. We have studied the sticking process of a colloid, suspended in a fluid medium by an optical tweezer, to a rigid substrate. The evolution of the frictional coupling between the two as a function of their separation is detected by the diffusivity of the particle and also by its phase-sensitive response to an in-plane external oscillatory drive applied to the substrate. On contact, the coupling changes abruptly from viscous to elastic for a rigid silica particle, whereas it evolves slowly with time, similar to ageing in glassy systems, for a soft and deformable polystyrene particle. Depending on the relative strengths of the particle–substrate interaction, the tweezer potential and the external drive, three regimes of dynamics—stuck, ageing and non-stuck—are observed in the dynamical phase diagram.
href={http://dx.doi.org/10.1038/nphys1105}>Nature Phys. 4 960-966 (2008)

Authors

P. Sharma, S. Ghosh and S. Bhattacharya