Liquid crystals are a good example of the use of soft-matter in electronic device applications, often for displays but also in optical films, spatial light modulators, switchable lenses and an increasing variety of applications. One of the more promising applications is in sensing devices, where small levels of certain chemicals or biological species at the liquid crystal interface cause drastic changes to the arrangement of the liquid crystal. Often the liquid crystal is contained within spherical droplets and the molecular alignment is mediated by appropriate surfactants at the solvent (usually water) boundary. This has the advantage that the droplet size can be accurately controlled by micro-fluidic methods. However, other geometries will also be investigated, such as patterned surfaces where both the shape and surface properties are varied to control the arrangement of the liquid crystal.
To make an electronic or optoelectronic nose, the sensor needs to include an array of elements each sensitive to a different vapour. Liquid crystals have a variety of different phases, phase sequences and symmetries, offering the potential for a wide range of detectable responses. This work will begin by investigating the relationship between liquid crystal material, its phases and symmetry, the surface properties of the aligning layer and its containment design and the optical response to a variety of gases. Optical and electrical methods for detecting the changes will be considered with the aim of fabricating operating devices. The work is envisaged to be experimental in nature, but could be adapted to include a high theoretical content, depending on the successful candidate.