title: Acoustic tracking of Cassie to Wenzel wetting transitions.
abstract: Many applications involving superhydrophobic materials require accurate control and monitoring of wetting states and wetting transitions. Such monitoring is usually done by optical methods, which are neither versatile nor integrable. This letter presents an alternative approach based on acoustic measurements. An acoustic transducer is integrated on the back side of a superhydrophobic silicon surface on which water droplets are deposited. By analyzing the reflection of longitudinal acoustic waves at the composite liquid-solid-vapor interface, we show that it is possible to track the local evolution of the Cassie-to-Wenzel wetting transition efficiently, as induced by evaporation or the electrowetting actuation of droplets.
authors.affiliation: Institute of Electronics, Microelectronics and Nanotechnology (IEMN, UMR 8520) Cité Scientifique, University of Lille Nord de France , Avenue Poincaré, BP 60069, 59652 Villeneuve d'Ascq, France.
authors.forename: Renaud
authors.initials: R
authors.lastname: Dufour
authors.forename: Nadine
authors.initials: N
authors.lastname: Saad
authors.forename: Julien
authors.initials: J
authors.lastname: Carlier
authors.forename: Pierre
authors.initials: P
authors.lastname: Campistron
authors.forename: George
authors.initials: G
authors.lastname: Nassar
authors.forename: Malika
authors.initials: M
authors.lastname: Toubal
authors.forename: Rabah
authors.initials: R
authors.lastname: Boukherroub
authors.forename: Vincent
authors.initials: V
authors.lastname: Senez
authors.forename: Bertrand
authors.initials: B
authors.lastname: Nongaillard
authors.forename: Vincent
authors.initials: V
authors.lastname: Thomy