My research group focuses on fundamental aspects of microscale transport phenomena in soft and biological matter. We use a combination of microscopy, microfluidics, and acoustofluidics, to provide precise, direct, dynamic measurements on the micro- and nano-scale. Through experiment, analysis and simulation we derive new insights in microscopic mechanisms and continuum-scale mechanics of structured fluids and interfaces. The areas of application of our research include:
- Formulated products: structured fluids, fluid dynamics, interfacial phenomena, rheology, particle-stabilized emulsions and foams, encapsulation, particle removal/recovery
- Biomedical imaging and drug delivery: biomedical colloids (microbubbles, vesicles, liposomes), ultrasound-induced bioeffects
- Bioprocessing: flow-induced cell rupture for product recovery (biofuels, biopharmaceuticals)
- Soft materials and self-assembly: self-assembly at fluid interfaces, stimuli-responsive materials
Ongoing and past projects:
Extreflow (ERC Starting GRANT)
The increasing demand for environmentally friendly, healthier, and better performing formulated products means that the process industry needs more than ever predictive models of formulation performance for rapid, effective, and sustainable screening of new products. Processing flows and end use produce deformations that are extreme compared to what is accessible with existing experimental methods. As a consequence, the effects of extreme deformation are often overlooked without justification.
Extreme deformation of structured fluids and soft materials is an unexplored dynamic regime where unexpected phenomena may emerge. New flow-induced microstructures can arise due to periodic forcing that is much faster than the relaxation timescale of the system, leading to collective behaviors and large transient stresses.
The goal of this research is to introduce a radically innovative approach to explore and characterize the regime of extreme deformation of structured fluids and interfaces. By combining cutting-edge techniques including acoustofluidics, microfluidics, and high-speed imaging, we will perform pioneering high-precision measurements of macroscopic stresses and evolution of the microstructure. We will also explore strategies to exploit the phenomena emerging upon extreme deformation (collapse under ultrafast compression, yielding) for new processes and for adding new functionality to formulated products.
These experimental results, complemented by discrete particle simulations and continuum-scale modeling, will provide new insights that will lay the foundations of the new field of ultrafast soft matter. Ultimately the results of this research program will guide the development of predictive tools that can tackle the time scales of realistic flow conditions for applications to virtual screening of new formulations.
Mechanical selectivity of lipid membrane rupture
Vesicle and cell rupture caused by large viscous stresses in ultrasonication is central to biomedical and bioprocessing applications. The flow-induced opening of lipid membranes can be exploited to deliver drugs into cells, or to recover products from cells, provided that it can be obtained in a controlled fashion. My group has demonstrated [Pommella A, Brooks NJ, Seddon JM, Garbin V, Selective flow-induced vesicle rupture to sort by membrane mechanical properties, Scientific Reports 5, 13163 (2015)] that differences in lipid membrane and vesicle properties can enable selective flow-induced vesicle break-up. By simultaneously deforming vesicles with different properties in the same flow conditions, we determined the conditions in which rupture is selective with respect to the membrane stretching elasticity. We identified conditions for robust selectivity based solely on the mechanical properties of the membrane. Our work should enable new sorting mechanisms based on the difference in membrane composition and mechanical properties between different vesicles, capsules, or cells.
Ultrasound-triggered, controlled release of nanoparticles
The self-assembly of solid particles at fluid-fluid interfaces is widely exploited to stabilize emulsions and foams, and in materials synthesis. The self-assembly mechanism is very robust owing to the large capillary energy associated with particle adsorption, of the order of millions of times the thermal energy for micrometer-sized colloids. Significant challenges arise when destabilization and particle removal are a requirement. We have developed a method [Poulichet V, Garbin V, Ultrafast desorption of colloidal particles from fluid interfaces, Proceedings of the National Academy of Sciences 112, 5932 (2015)] for ultrafast desorption of nanoparticles from the interface of particle-stabilized microbubbles. Complete removal of colloid monolayers from bubbles, triggered by ultrasound, is achieved in under a millisecond. Our method should find a broad range of applications, from nanoparticle recycling in sustainable processes to programmable particle delivery in lab-on-a- chip applications. This work also addresses the emerging need for methods to recover interfacial particles from emulsions and foams in applications ranging from controlled release to interfacial catalysis and gas storage.