Surface acoustic wave two-dimensional transport and location of microdroplets using echo signal

Digitalized microfluidics is dealing with microdroplet actuation and location. We propose the implementation of a surface acoustic wave (SAW) echo method so as to move and to locate a microdroplet from a single interdigital transducer (IDT). A prototype working at 20MHz demonstrates the ability of this method to achieve the goal with submillimeter accuracy quite sufficient for aimed biologic applications. The tested platform fitted with one IDT built on a LiNbO3 substrate allows the tracking of water droplets actuated by SAW running free or squeezed under a cover for biological treatments in a lab on chip.