Research on excitation technology of high-throughput ultrasonic micro-separator based on micro-nano fabrication

Abstract

The excitation technology of ultrasonic standing wave field is the core key to realize ultrasonic separation. This paper analyzes the excitation technology of (1, 1) mode ultrasonic separation of high-throughput ultrasonic micro-separator. There are two main problems: the coexistence of multiple modes in the separation cavity and the insufficient acoustic radiation force. In order to solve these two problems, this paper uses integrated circuit micromachining technology to process the ultrasonic micro-separator. The depth dimension of the cavity reaches 200 ± 0.5 µm, and the verticality of the side wall of the cavity reaches 83.36°. The degree of SFPD (Site Focal Plane Deviation) is less than or equal to 0.25 µm. Besides, this paper proposes an excitation method of saw-tooth frequency sweep of two anti-phase acoustic drivers. Finally, the experiments of the separator processed by the processing method proposed in this paper shows that, the excitation method proposed in this paper can effectively excite the (1, 1) mode, and shortens the time for the pattern formation of particle convergence, which greatly improves the separation efficiency. The separation throughput (flow rate) in one single cavity in this work can reach to 100 µl/min. It provides an effective basis for ultrasonic micro-separation technology.