Design of a multi-element transducer for large volume acoustophoretic phase separation

Abstract

Efficient separation technologies for multi-component liquid streams that eliminate waste and reduce energy consumption are needed. In previous experiments around this novel platform technology, a single element transducer has been used to generate a high intensity three-dimensional ultrasonic standing wave resulting in an acoustic radiation force that is larger than the combined effects of fluid drag and buoyancy. Acoustic trapping of particles followed by enhanced gravitational settling is used to separate the secondary phase. A typical transducer is made of a PZT-8 2-MHz ceramic. This work reports on the comparison of the performance of a single element transducer to that of a multi-element transducer. Parametric simulation studies of multi-element transducer designs were performed to accurately predict the acoustic pressure field in the fluid flow with the goal of generating large acoustic radiation forces to assist in phase separation. COMSOL Multiphysics ¯ was used to run simulations and results were compared to an experimental prototype that consisted of a 2-in. by 1-in. flow chamber driven by a 1-in. by 1-in. 2-MHz transducer. The designs of the multi-element transducers consisted of two PZT-8 2-MHz transducers; one consisting of 16 elements and another of 25 elements. [Work supported by NSF PFI:BIC 1237723.]