  Circular swimmers with tunable orbit radius and chirality are gaining
attention due to their potential to illustrate novel collective phases in
simulations and synthetic and biological active matter. Here, we present a
facile experimental strategy for fabricating active rotors using chemically
cross-linked clusters of Janus colloids. Janus clusters are propelled by
induced charge electrophoresis in an alternating electric field. We demonstrate
capillary-assisted assembly as a feasible path toward expanding the fabrication
process to get large amounts of uniform circular clusters. Systematic studies
of the Janus clusters reveal circular motion with tunable angular velocity,
orbit radius, and chirality and a relation between the radius of gyration of
the cluster and their rotational dynamics. Importantly, clusters with uniform
azimuthal angles behave distinctly exhibiting larger orbit radii, while those
with random angles exhibit higher angular velocities and smaller radii. We also
validate the kinetic model for clusters beyond dimers. Collectively, our
studies highlight that Janus clusters as promising candidates as controlled
circular rotors with tunable properties and, hence in the future, will
facilitate studies on the collective behaviors of synthetic chiral rotors.
