Self-Reporting and Self-Regulating Liquid Crystals Triggered by Motile Bacteria*

Nematic liquid crystals (NLC) are structured liquids within which molecules are organized with long-range orientational order. This order leads to anisotropic elastic and dielectric properties. The orientational order of NLCs is readily perturbed by external forces, including interfacial shear stresses. In this presentation, we will show that the motion of bacterial cells near the interface between a bulk aqueous phase and an immiscible NLC can generate interfacial shear stresses that lead to reorientation of the NLC and an optical response. The reorientation of the NLC will be shown to also lead to changes in elastic and electrical double layer forces acting between colloidal inclusions (microcargo) within the NLC phase, thus triggering their release into the aqueous phase. This network of interactions within the LC leads to self-regulated release of microcargo containing biocidal agents in response to the arrival of motile bacterial cells.