Programmable Liquid Handling by a Multi-Resonant Transducer Array with Frequency Division Multiplexing

This paper reports a novel method of liquid handling by an acoustic transducer array using frequency division multiplexing. Lamb wave transducers with different resonant frequencies can be designed by simply tuning the width of electrode strip. In this paper, an octagon patterned transducer, consisted of eight Lamb wave transducers to focus acoustic energy, is used as a cell. Then, transducer cells with different resonant frequencies are connected in parallel to achieve frequency division multiplexing. By controlling excitation frequency, we demonstrate that each cell can drive liquid to form a fountain and manipulate a droplet target to travel on the liquid surface. This method of liquid handling is free from limitations of conventional strategies, such as complicated circuits and contaminations.