Microrheometry research opportunities

Multi-researcher programs:

• Integrate microfluidics and neutron science.
• Screening methods for complex fluid formulation, e.g. high volume fraction gel emulsions.

For NRC postdoctoral applicants, proposals are invited to address the following:

• Select a small aspect of the larger opportunities listed just above.

Interfacial rheology

• How do interfacial viscosities depend on interfacial composition? Identify a model system (~ 400 nm particles on an interface, so that high resolution optical microscopy can measure both their velocities and concentration).
• How inhomogeneous is the interfacial viscoelasticity on a particle-laden interface? Multi-particle tracking on the interface. Coupling to flow.
• Combine neutron reflectivity and interfacial rheology. How does interfacial deformation influence competitive adsorption?
• Does drop size affect dispersion of toxic components during an oil spill? Rate of mass transfer across interfaces.
• Is there a relationship between protein interfacial rheology and protein aggregation?
• Improve droplet-based interfacial rheology methods for: greater sensitivity, broader window of interface age, and facility for high throughput.

Protein, particle and gel rheology

• Measure the fast time dynamics of particles or emulsion drops in jammed systems and explore relationships to slow relaxation processes.
• Wormlike micelles in porous media; structure/flow properties.
• Combined rheology and microscopy. When integrated so far, the sampled volume in rheology is much larger than in microscopy. What about matching these volumes? Note that rheology of collagen gels is remarkably size dependent.How to measure heterogeneous force transmission in colloids and gels?
• What influences particle diffusion in hydrogels, such as collagen? How does diffusivity relate to network homogeneity, to mechanical deformation, to macromolecular crowding? Metrology issues: the best method to measure diffusivity and deformation induced diffusivity; using diffusivity as gel characterization method.
• How does shear-induced diffusion depend on particle interactions?

Polymer rheology

• Microfluidic normal stress meter.

MEMS rheometer

• Transfer MEMS rheometer technology to collaborators. Improve ease of use.
• Combined rheology and microscopy (as noted above).