Roughness induced rotational slowdown near the colloidal glass transition

Interaction of Active Janus Colloids with Tracers

“…At this edge where the tracers accumulate, they interact through their topological characteristics and surface roughness, which can cause a significant slow-down in their translation and rotational dynamics, leading to a jammed state. 53 This behavior of While most of the active JPs remain mobile most of the times, it was observed that sometimes mobile active JPs encounter tracer(s) which get stuck to the leading silica side, forming a jammed layer, sometimes multiple layers, obstructing the movement of the JP at a fixed location (see Figure 9b). These stuck active JPs have their Janus plane perpendicular to the bottom wall and they demonstrate a fluidlike depletion zone similar to that observed by Katuri et al 47 Occasionally, it was observed that if the jammed tracer layer is released, these JPs regain movement.…”

“…Unlike the previous case, for such long-time collisions, on the SiO 2 side the layer of tracers remains stuck. At this edge where the tracers accumulate, they interact through their topological characteristics and surface roughness, which can cause a significant slow-down in their translation and rotational dynamics, leading to a jammed state . This behavior of formation of an immobile layer of tracers on the leading edge varies randomly among the observed JPs.…”

3-D rotation tracking from 2-D images of spherical colloids with textured surfaces

“…More recently, Ilhan et al demonstrated the tracking of the 3-D rotations of colloidal particles having an overall spherical shape, but presenting a non-uniform fluorescence signal due to the presence of fluorescent asperities onto their surfaces (raspberry particles) 39 . They then used these particles to probe the effect of surface roughness on the rotational dynamics of a colloidal suspension approaching the glass transition 40 .…”

“… 39 They then used these particles to probe the effect of surface roughness on the rotational dynamics of a colloidal suspension approaching the glass transition. 40 …”

“…39 They then used these particles to probe the effect of surface roughness on the rotational dynamics of a colloidal suspension approaching the glass transition. 40 Currently, most experimental approaches to directly measure 3-D rotation require three-dimensional imaging, typically achieved by performing z-scans with a confocal microscope. Besides the requirement for sophisticated equipment, this approach is ill-suited for the rapid tracking of particle rotations, as images from different focal planes must be acquired continuously (z-stacks), introducing significant delays in the effective volumetric frame rate.…”