Acoustic trapping of particle by a periodically structured stiff plate

Abstract

Acoustic tweezers have found potential applications in both the physical and life sciences in the past two decades due to their abilities of contactless, controllable and noninvasive trapping and manipulating micro-scale objects regardless of material transparency. Approaches to acoustic trapping of micro-objects required large field intensities. They are usually generated directly by acoustic transducer, cannot be redesigned easily, nor can the corresponding acoustic radiation forces be modulated efficiently. Recently, the artificial structures, such as phononic crystal or metamaterials, can provide a facile way of controlling the field distribution of acoustic wave. These artificial fields may have potential application in acoustic manipulation. In this work, we demonstrate that a geometrical modulated trapping force can exert on an object as it is near the surface of structured artificial brass plate at resonance frequency. The mechanism and condition of this trapping effect are discussed via the field and force analyzing, respectively.