“…Its usefulness is also suggested by the low particle concentrations required. In fact, the cluster formation is strongly enhanced by the presence of confining geometries, as experimentally shown for bacteria [39][40][41] or artificial microswimmers [13,42], since active particles accumulate near boundaries [43][44][45][46], wall channels [47][48][49][50][51], and obstacles [52][53][54][55]. The employment of active particles, instead of passive colloidal particles, to control the channel occlusion leads to further advantages.…”