Role of cohesion in the flow of active particles through bottlenecks

Abstract

We experimentally and numerically study the flow of programmable active particles (APs) with tunable cohesion strength through geometric constrictions. Similar to purely repulsive granular systems, we observe an exponential distribution of burst sizes and power-law-distributed clogging durations. Upon increasing cohesion between APs, we find a rather abrupt transition from an arch-dominated clogging regime to a cohesion-dominated regime where droplets form at the aperture of the bottleneck. In the arch-dominated regime the flow-rate only weakly depends on the cohesion strength. This suggests that cohesion must not necessarily decrease the group’s efficiency passing through geometric constrictions or pores. Such behavior is explained by “slippery” particle bonds which avoids the formation of a rigid particle network and thus prevents clogging. Overall, our results confirm the general applicability of the statistical framework of intermittent flow through bottlenecks developed for granular materials also in case of active microswimmers whose behavior is more complex than that of Brownian particles but which mimic the behavior of living systems.

Role of liquid driving on the clogging of constricted particle suspensions

“…2020, 2021; Knippenberg et al. 2022). The suspension consists of monodisperse spherical polystyrene particles (Microparticles GmbH) of diameter , 21.7 and ( %).…”

“…This specific design, similar of that used in previous studies (Marin et al 2018;Souzy et al 2020), forms a two-dimensional nozzle converging towards the neck. Particles and liquid have been chosen carefully to avoid buoyancy effects, particle aggregation and particle deposition at the microchannel walls, an effect that has been analysed previously by many (Sendekie & Bacchin 2016;Cejas et al 2017;Dressaire & Sauret 2017;Delouche et al 2020Delouche et al , 2021Knippenberg et al 2022). The suspension consists of monodisperse spherical polystyrene particles (Microparticles GmbH) of diameter d = 19.0, 21.7 and 33.0 μm (±3 %).…”

“…If this happens, then the flow of particles is resumed (figure 1b) and a burst of particles escapes until the development of a new clog arrests the flow again (figure 1c). Note that arches are stabilized by the mutual friction among particles (Wyss et al 2006;Agbangla, Bacchin & Climent 2014;Sendekie & Bacchin 2016;Knippenberg et al 2022), implying that, despite the presence of electrostatic stabilization, particle-to-particle contact is unavoidable. However, these contacts are not long-lasting as particles separate downstream of the constriction upon resuming the flow.…”

“…2006; Agbangla, Bacchin & Climent 2014; Sendekie & Bacchin 2016; Knippenberg et al. 2022), implying that, despite the presence of electrostatic stabilization, particle-to-particle contact is unavoidable. However, these contacts are not long-lasting as particles separate downstream of the constriction upon resuming the flow.…”

Capture and transport of rod-shaped cargo via programmable active particles

“…Artificial steering signals can, therefore, be computed externally before being inserted back into the system. Examples of phenomena studied with feedback-loop experiments are visual stimuli-induced groups 7 , swirl formation 6 , and cohesion-based clogging of geometric constrictions 8 .…”