Probing properties of fluid interfaces at the scale of picolitre droplets and Genetically-encoded interfaces
Saikat Saha (ENS, Paris)
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