Using liquid crystals to measure shear stress in cells

Cellular stresses are involved in many di erent processes such as wound healing and em- broyonic development. Currently, measuring cellular stresses is di cult and uncommon. Mea- surements of stress are usually taken indirectly by measuring strain which is related to stress using a linear relationship. Biological tissues, however, do not follow common stress strain rela- tionships complicating using this common technique. Previous research has shown that liquid crystals can be used to directly measure shear stresses. Other research suggests that certain types shear sensitive liquid crystals are non toxic to live cells. The goal of this project was to investigate using liquid crystals to directly measure shear stresses in live cells. Preliminary research involved investigating simple techniques, such as sim- ple spreading, to add liquid crystals to live cell cultures in hopes of measuring cellular stresses. However, issues with liquid crystals being hydrophobic pushed the research to investigate using partially exposed liquid crystals embedded in a polystyrene matrix. Various mixtures were created containing dissolved liquid crystals and polystyrene. These mixtures were then sprayed onto glass cover slides to be a substratum for cellular growth. Also, they were placed into custom made ow chambers to be calibrated for color changes resulting from shear stresses. The results of the experiment revealed that the partially exposed polymer dispersed liquid crystals were insensitive to shear stresses. However, the cells did grow on the arti cial sub- stratum with embedded liquid crystals. Therefore, a methodology has been created which can be used to embed materials or substances in a polystyrene matrix on which cells grow.. This provides the foundation for future research into using liquid crystals to measure shear stresses and provides a method for growing cells in the presence of various substances that need to be embedded in a solid matrix