Laser-induced thermocapillary deformation of fluid surfaces has emerged as a promising tool to precisely characterize the thermophysical properties of pure fluids. However, challenges arise for nanofluid (NF) and soft bio-fluid systems where the direct interaction of the laser generates an intriguing interplay between heating, momentum, and scattering forces which can even damage soft bio-fluids.
Here to address these challenges, in a recent collaborative work with Prof. Jean Pierre Delville from University of Bordeaux and Prof. Nenad Miljkovic from UIUC, we report a versatile, pump-probe-based, rapid, and non-contact interferometric technique that resolves interface dynamics of complex fluids with precision of approximately 1 nm in thick-film and 150 pm in thin-film regimes below the thermal limit without the use of lock-in or modulated beams. We characterize the thermophysical properties of complex NF in three exclusively different types of configurations. Our results suggest a general approach for precision measurements of complex NFs, bio-fluids, and optofluidic devices. This paper, entitled "A versatile interferometric technique for probing the thermophysical properties of complex fluids", is published in Light: Science & Applications. Congratulations to Gopal, Sajed, Longnan, and all co-authors!