Acoustic manipulation of microparticles using a piezoelectric phononic crystal plate

Abstract

Acoustic tweezer is a promising device for manipulating particles, which does not need contact does not cause damage, or requires transparent materials. 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 the precise shaping of the acoustic fields. Traditionally, there are mainly two types of acoustic tweezers: bulk acoustic wave (BAW) and surface acoustic wave (SAW). The SAW-based acoustic tweezer operates at high frequencies, realizing precise manipulation. The BAW-based acoustic tweezer operates at lower frequencies and requires artificial structure on the transducer surface to shape the field. However, the separation of the artificial structure from the transducer brings complexity and instability into the manipulation process. In this study, we propose a novel approach to overcoming these challenges, that is, using piezoelectric phononic crystal plates to integrate the transducer and acoustic artificial structure. By designing the thickness, periodicity, and electrode width of the piezoelectric phononic crystal plate, we can excite the <i>A</i><sub>0</sub> 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 to be trapped or levitated on the surface. To validate this approach, an experimental device is constructed, and successful particle manipulation is achieved by using Lamb wave mode or periodic resonant mode through using the piezoelectric phononic crystal plate. This technological breakthrough serves as a crucial foundation and experimental validation for developing the compact, low-energy and high-precision acoustic tweezers.