  Accumulation of particles while flowing past constrictions is a ubiquitous
phenomenon observed in diverse systems. Some of the common examples are jamming
of salt crystals near the orifice of salt shakers, clogging of filter systems,
gridlock in traffics etc. For controlled studies, accumulation events are often
examined as clogging process in microfluidic channels. Experimental studies
thus far have provided with various physical insights, however, they fail to
address commonly encountered accumulation events relevant to human health such
as dental and arterial plaques. We simulate arterial plaque like accumulation
events by flowing colloidal microspheres over micro-structured barriers in
microfluidic environment. Our experiments reveal the role of electrostatic,
contact and hydrodynamic forces in facilitating plaque-like build up events. A
decrease in Debye length (electrostatic repulsion) between interacting surface
by two orders leads to only a minor increase in accumulation. In contrast, an
increase in the roughness by 3 times results in dramatic rise of accumulation.
