Host: Sarah Perry
Liquid crystals (LCs) have been used widely to create reconfigurable materials that report optically their environment, including changes in electric fields (smart phone displays), temperature (thermometers) or mechanical shear, and the arrival of chemical and biological stimuli (sensors). This presentation will describe how the same set of stimuli can also trigger pulsatile or continuous release of microcargo (aqueous microdroplets or solid microparticles and their chemical contents) that are trapped initially within the LCs by the anisotropic elasticity of the LCs. The resulting LC materials self-report and self-regulate their chemical response to targeted physical, chemical and biological events in ways that can be preprogrammed via an interplay of elastic, electrical double layer, buoyant and shear forces in diverse geometries (e.g., wells, films, and emulsion droplets). The LC materials can carry out complex functions that go beyond conventional materials for controlled release, such as by optically reporting a stimulus (e.g., mechanical shear stresses generated by motile bacteria) and then responding in a self-regulated manner via a feedback loop (e.g., to release the minimum amount of biocidal agent required to cause bacterial cell death). Other potential applications of LCs as “sentient materials” will be discussed.