MRI: Acquisition of a Confocal Microscope Rheometer for Structural Characterization of Complex Fluids & Soft Materials Under Shear

University Of Pennsylvania, Philadelphia PA

Investigators

Abstract

Complex fluids are a broad class of materials widely used in processes spanning the chemical, petroleum, pharmaceutical and food industries. They are also abundant in natural environments (for example, soil and mud) as well as in the human body (for example, mucus and reproductive fluids). Complex fluids may be considered 'soft', in the sense that they flow or distort easily in response to external forces. Many fascinating macroscopic responses of complex fluids containing particles, polymers, (bio)molecules, surfactants, or liquid crystals, have been widely reported in the literature. Characterizing the mechanical properties and microstructure of complex fluids and biological materials remains a challenge. The main issue is that one needs to precisely measure the material bulk response (or rheology) while simultaneously characterizing its microstructure. To that end, this project involves developing an instrument that incorporates a sensitive rheometer with a dynamic range that allows precise application of kinematic deformation coupled with a confocal microscope that provides real space, high-magnification, time-resolved spatial information in three dimensions. This research project aims to develop a confocal rheometer microscope by combining two commercially-available instruments, a confocal microscope and a stress-controlled rheometer. This new apparatus will allow researchers to impose precise kinematic deformation (i.e. shear, steady or time-dependent) onto a desired material while simultaneously characterizing the fluid microstructure and measuring the bulk fluid response. By incorporating both a high precision rheometer and a confocal microscope into one system, the project researchers will be able to conduct cutting edge experiments that relate 3-dimensional microstructure to bulk properties. The research project also could lead to new fundamental understanding of the mechanical and chemical forces that govern the dynamics of complex and soft materials and to new applications via the development of novel materials. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.