Characterization of the state of a droplet on a micro-textured silicon wafer using ultrasound

N. Saad (1, 2) , R. Dufour (1, 3) , Pierre Campistron (1) , Georges Nassar (1) , Julien Carlier (4) , M. Harnois (1) , B. Merheb (2) , Rabah Boukherroub (3) , V. Senez (1) , J. Gao (1) , V. Thomy (1) , M. Ajaka (2) , Bertrand Nongaillard (1)

1 IEMN - Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520
2 LU / ULB - الجامعة اللبنانية [بيروت] = Lebanese University [Beirut] = Université libanaise [Beyrouth]
3 IRI - Institut de Recherche Interdisciplinaire [Villeneuve d'Ascq]
4 MAMINA - IEMN - Matériaux et Acoustiques pour MIcro et NAno systèmes intégrés - IEMN

In this work, we propose acoustic characterization as a new method to probe wetting states on a superhydrophobic surface. The analysis of the multiple reflections of a longitudinal acoustic wave from solid-liquid and solid-vapor interfaces enables to distinguish between the two well known Cassie-Baxter and Wenzel wetting configurations. The phenomenon is investigated experimentally on silicon micro-pillars superhydrophobic surfaces and numerically using a finite difference time domain method. Numerical calculations of reflection coefficients show a good agreement with experimental measurements, and the method appears as a promising alternative to optical measurement methods

Domaines: Mécanique des fluides [physics.class-ph]

N. Saad, R. Dufour, Pierre Campistron, Georges Nassar, Julien Carlier, et al.. Characterization of the state of a droplet on a micro-textured silicon wafer using ultrasound. Journal of Applied Physics, 2012, 112 (10), pp.104908. ⟨10.1063/1.4767223⟩. ⟨hal-00788344⟩