The development of micro- and nano-fluidics raises many challenging problems concerning flow and dissipation in confined liquids. The moving contact line issue is another example of unanswered question requiring investigation of liquids at the nanometer scale. In order to address some of these issues, Thierry's group uses atomic force microscopy (AFM) with dedicated tips ended by a nanocylinder (20 to 200 nm in diameter). In frequency-modulation mode (FM-AFM), monitoring frequency-shift and dissipation signals during the partial immersion of the nanofiber in a liquid allows investigating various contributions to the probe-liquid interaction:
- The dissipation in the viscous layer around the nanofiber .
- The dissipation in the nanomeniscus and its dependence with respect to contact angle .
- The effective spring constant of the liquid interface .
This study shows that FM-AFM combined with non-conventional AFM tips provides quantitative measurements of the mechanical properties of simple liquids down to nanometer scale, which may be extended to complex fluids.
Thierry Ondarçuhu is research director at the IMFT's Interfaces research group. His research activities include wetting and capillarity at the nanometer scale, nanohydrodynamics, wetting of heterogeneous surfaces, reactive wetting, atomic force microscopy, focused ion beam and liquid nanodispensing. Together with Jean-Pierre Aimé he edited „Nanoscale liquid interfaces: wetting, nanopatterning and force microscopy at molecular scale“ (2013).
 J. Dupré de Baubigny, M. Benzaquen, C. Mortagne, C. Devailly, J. Laurent, A. Steinberger, J.-P. Salvetat, J.-P. Aimé, T. Ondarçuhu, Phys. Rev. Fluids, 1 (2016) 044104.
 C. Mortagne, M. Benzaquen, K. Lippera, P. Tordjeman, T. Ondarçuhu, Phys. Rev. Fluids. Rapid Comm., 2 (2017) 102201(R).
 J. Dupré de Baubigny, M. Benzaquen, L. Fabié, M. Delmas, J.-P. Aimé, M. Legros, T. Ondarçuhu, Langmuir 31 (2015) 9790-9798.
Venue: L2|06, Room 100
Date: March 25, 2019, 11:00-12:00 hrs