title: Detection and high-precision positioning of liquid droplets using SAW systems.
abstract: The capability to accurately handle liquids in small volumes is a key point for the development of lab-on-chip devices. In this paper, we investigate an application of surface acoustic waves (SAW) for positioning micro-droplets. A SAW device based on a 2 x 2 matrix of inter-digital transducers (IDTs) has been fabricated on a (YXI)/128 degrees LiNbO3 substrate, which implies displacement and detection in two dimensions of droplets atop a flat surface. Each IDT operates at a given frequency, allowing for an easy addressing of the active channel. Furthermore, very low cross-talk effects were observed as no frequency mixing arose in our device. Continuous as well as pulsed excitations of the IDTs have been studied, yielding, respectively, continuous and step-by-step droplet displacement modes. In addition, we also have used these two excitation types to control the velocity and the position of the droplets. We also have developed a theoretical analysis of the detection mode, which has been validated by experimental assessment.
authors.affiliation: Laboratoire FEMTO-ST/LPMO, Unité Mixte de Recherche Centre National de la Recherche Scientifique, 6174, Université de Franche Comté, F-25044 Besançon Cedex, France.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Bennès
authors.forename: Sébastien
authors.initials: S
authors.lastname: Alzuaga
authors.forename: Frédŕic
authors.initials: F
authors.lastname: Chérioux
authors.forename: Sylvain
authors.initials: S
authors.lastname: Ballandras
authors.forename: Pascal
authors.initials: P
authors.lastname: Vairac
authors.forename: Jean-Francois
authors.initials: JF
authors.lastname: Manceau
authors.forename: Francois
authors.initials: F
authors.lastname: Bastien