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TOPIC:            Engineering Injectable Complex Fluids Using Single-Drop Extensional Rheology

SPEAKER:      Michelle Calabrese, Assistant Professor at University of Minnesota

DATE:              THURSDAY, February 17th      ** Please note the meeting is on THURSDAY this month **

TIME:               6:00 – Introduction

                             6:05 - Carrer Discussion

                             6:15 Technical Presentation

                             7:15 Q&A

COST:               Free, Registration Required          

LOCATION:    Online Zoom meeting

ABSTRACT:   Injectability, sprayability, and printability in soft materials are dictated by the flow properties under extensional “stretching” flows. Until recently, the extensional rheology of dilute protein and polymer solutions has been sparsely studied due to experimental limitations. Most extensional rheology devices yield mixed shear and extensional flows, cover limited extension rates, require multiple loadings, and are not commercially available. However, capillary-driven thinning of a liquid bridge – in which filament thinning can be mathematically described by distinct behavioral regimes accounting for inertial, viscous, elastic, and capillary forces – can be used to accurately measure rheological parameters.  To measure scarce materials and low viscosity fluids in truly small volumes, we have developed instrumentation for simultaneous droplet-based extensional rheology and surface tension measurements in <10 μL/trial over a range of temperatures, humidities, and organic solvents. We demonstrate the utility of capillary-driven thinning to determine injectability and coatability in protein therapeutics and polymer solutions. For example, common excipients added to stabilize proteins in shear flows produce adverse behavior in extension that can cause protein denaturing. For polymer solutions in organic solvents, we employ a new environmental control system to confirm scaling relationships for the first time, and also show that evaporation effects during measurement can depend more on polymer mobility than solvent vapor pressure. These case studies illustrate the utility of solution extensional rheology for predicting injectability and coatability, enabling rapid formulation screening using a single drop.

SPEAKER BIOGRAPHY:  Michelle A Calabrese is an assistant professor in the Department of 91���˶���Ƶ Engineering and Materials Science at the University of Minnesota. She received her BS in 91���˶���Ƶ Engineering from the University of Pennsylvania in 2012. She completed her PhD in 91���˶���Ƶ Engineering at the University of Delaware in 2017, where she focused on developing new techniques in rheology and neutron scattering to understand the flow properties of complex fluids. Following her postdoc in chemical engineering at MIT, she joined the faculty at UMN in mid-2019. Her research group employs rheology, soft matter physics, and polymer and nanoparticle synthesis to address a range of fundamental and applied problems in polymer and soft materials engineering. Her recent recognitions include the 3M Non-tenured Faculty Award, NSF CAREER Award, and NIH NIDCD Early Career Research Award (R21).