  A trapping mechanism for propelled colloidal particles based on an
inhomogeneous drive is presented and studied by means of computer simulations.
In experiments this method can be realized using photophoretic Janus particles
driven by a light source, which shines through a shading mask and leads to an
accumulation of the particles in the passive part. An equation for an
accumulation parameter is derived using the effective inhomogeneous diffusion
constant generated by the inhomogeneous drive. The impact of particle
interaction on the trapping mechanism is studied, as well as the interplay
between passivity-induced trapping and the emergent self-clustering of systems
containing a high density of active particles. The combination of both effects
makes the clusters more controllable for applications.
