DescriptionKnown for their high sensitivity to their surroundings coupled to rapid optical feedback, liquid crystals have attracted considerable interest for sensing applications. Many existing technologies are good at telling that there’s a contaminant of some kind (such as a volatile gas, something that changes temperature, or a surface active molecule), and this responsiveness can be incorporated into platforms such as fibers, rubbers, and gels. However, not much work has looked into whether or not we can actually extract information about what exactly is present: for example, is it possible to distinguish between surfactants and fats present? Can we use a liquid crystal-based sensor to detect if a specific molecule or protein is present in a system? And can we also extract information about how much of something is present?
In this presentation, I present some advances we have made in liquid crystal interfaces to rapidly detect the identity and quantity of a target molecule present in a system. First, we look at using cholesteric liquid crystal droplets to probe the identity of specific fatty acids, lipids, and tensides present in an aqueous medium. Owing to how differently molecules with different head and tail groups can pack at the LC-water interface, we can correlate this to a color signature specific to a given molecule by simply analyzing the ratios of red, green, and blue present. Cholesteric LC droplets, through simple suspension in a PVA solution, can additionally be dried on glass slides, retaining their responsiveness to amphiphiles while allowing us to also unveil the dynamics of the alignment switching process. We additionally can use cholesteric LC droplets for in vivo sensing inside zebrafish, probing the presence of certain fatty acids that may be the byproducts of diseased and unhealthy gut microbiota.
Secondly, I will present work on using LC interfaces as platforms for immunoassays. Through a sequence of biotin-avidin linkages, we can sensitize an interface of a liquid crystal to the presence of a given molecule through attachment of antibodies. This functionalized interface is specific, responding to the presence of a positive control but showing no response in the presence of a negative control. This gives us another approach to detect, in particular, less surface-active macromolecules of biological relevance, such as pathogens or other signs of disease.
|Period||27 Jun 2022 → 30 Jun 2022|
|Event title||Rank Prize Symposium for Optoelectronics (Liquid Crystal Technologies for Light)|
|Location||Grasmere, United Kingdom|
- Sensing Liquid Crystals