Driven lock-and-key colloidal particles for directed assembly

In nematic lock-and-key interactions, as in biology, colloidal particles interact preferentially with particular sites. Nematic lock-and-key recognition, studied previously near wavy walls, relies on particles interacting elastically with curved boundaries to minimize their elastic energy. We extend this concept by introducing driven lock-and-key particles, inherently topologically distinct from the wavy wall. The driven lock-and-key particle is a multi-armed structure with curvature designed for multiple modes of interaction with passive colloidal particles including (i) lock-and-key interactions in a well with a hyperbolic hedgehog companion defect pointing outwards, (ii) lock-and-key interactions on a curved arm with companion defect pointing inwards, and (iii) disclination loop-dipole chaining. The lock-and-key particle’s design also promotes the formation of a disclination loop whose location can be managed by controlling the particle’s orientation, and whose stability can be manipulated for controlled release and for introduction of non-equilibrium structures for assembly. The mobility of the lock-and-key colloid provides new degrees of freedom for combined bottom up and top down materials assembly.