Seminar Saikat Saha

Probing properties of fluid interfaces at the scale of picolitre droplets and Genetically-encoded interfaces

Saikat Saha¹, Cécile Monteux², Damien Baigl¹

1. CPCV, Department of Chemistry, École Normale Supérieure, PSL University, Sorbonne Université, CNRS, 75005 Paris, France
2. Sciences et Ingénierie de la Matière Molle, École Supérieure de Physique et de Chimie Industrielles de la Ville de Paris, 75005 Paris, France
   E-mail : saikat.saha@ens.psl.eu

The mechanical properties of complex fluid interfaces dictate how the emergent behaviours of the microstructure manifest as functional properties. I will briefly discuss my previous work on utilising acoustic-driven bubble oscillations to interrogate the broad-spectrum deformation behaviour of complex interfaces. Next, I will describe my current efforts in developing an
experimental microfluidic framework to characterise interfacial viscoelasticities for picolitre volume droplets, particularly useful for precious quantities. Fundamentally, it offers a simple approach to probe mechanical properties in regimes of length-scales and time-scales where information from conventional macroscopic rheometric methods cannot always be extrapolated to. Finally, I will describe our exploratory work on programmable soft materials wherein a system is provided with a synthetic genome in which all the properties of the soft material could virtually be encoded. This combined with cell-free expression of interfacially-active proteins enables the control of surface tension and interfacial elasticity at a genetic level. In effect, it permits a closed system – of fixed composition, with the same starting raw materials – to dynamically evolve its own interfacial properties to have autonomous spatio-temporal effects. This has allowed us to program dynamic surface tension profiles as well as create fluid propulsion at the macroscale, which to our knowledge, is the first example of genetically-driven surface tension regulation and fluid transport.

Keywords: viscoelastic interfaces, microfluidics, programmable soft matter, DNA