Acoustic manipulation of microparticles using a piezoelectric phononic crystal plate

Abstract

Acoustic tweezers offer a promising device for manipulating particles without the need for contact, causing damage, or requiring material transparency. They have diverse applications in cell separation, tissue engineering, and material assembly. To control particle movement, this technology relies on the exchange of momentum between the particle and the acoustic field, generating an acoustic radiation force. Achieving high-performance acoustic tweezers necessitates precise shaping of the acoustic fields. Traditionally, there are two main categories of acoustic tweezers: Bulk Acoustic Wave (BAW) and Surface Acoustic Wave (SAW). SAW-based acoustic tweezers operate at high frequencies, offering precise manipulation. Meanwhile, BAW-based acoustic tweezers operate at lower frequencies and require artificial structure on the transducer surface to shape the field. However, the separation of the artificial structure from the transducer introduces complexity and instability to the manipulation process. In this study, we propose a novel approach to overcome these challenges by integrating the transducer and acoustic artificial structure using piezoelectric phononic crystal plates. By designing the thickness, periodicity, and electrode width of the piezoelectric phononic crystal plates, we can excite the A₀ Lamb wave mode and the periodic resonant mode, resulting in a periodic gradient field and a periodic weak gradient field, respectively. These fields enable particle trapping or levitation on the surface. To validate this approach, an experimental device was constructed, and successful particle manipulation using Lamb wave mode or periodic resonant mode was achieved through the use of piezoelectric phononic crystal plates. This technological breakthrough serves as a crucial foundation and experimental validation for the development of compact, low-energy and high-precision acoustic tweezers.