Microfluidic acoustic valve for capturing locomotive microorganism without anesthesia

The capture of locomotive small organisms is challenging but interesting. In this study, we developed a method to capture Paramecium with acoustic valve. Constructed by the focused surface acoustic waves (FSAW), acoustic valve can be used to block the dispersed phase in liquid flow. Under the joint action of acoustic radiation force and drag force, Paramecium can be successfully confined in a narrow space in the channel without losing its movement ability. By adjusting the applied voltage and the inlet pressure, the Paramecium can be allowed to pass, but the Paramecium cysts get captured. This acoustic device is potential in biochemical experiments, providing a new method for capturing or sorting micro swimmers. (a) Schematic diagram of acoustic valve capturing Paramecium. (b, c, d) Comsol simulation of Paramecium capture. Top view (b, x-z plane), front view (c, x-y plane) and side view (d, y-z plane) of the acoustic pressure field. (e) Trajectory (yellow dotted line) of captured Paramecium in front of acoustic valve. The positions of Paramecium were cut from multiple moments in the video and spliced together. The numbers ① to ⑨ are located on one end of Paramecium, and the rotation of the number represents the posture of Paramecium at that time. (f) ⓪ represents the position of Paramecium at 0 ms. In order to distinguish six and nine after rotation, ⑥ stands for six and ⑨ stands for nine. (b) Images of Paramecium's position from ① to ⑨. (g) Paramecium cyst got captured by acoustic valve. The voltage was 25 V and the pressure was 1500pa. • A non-contact, non-anesthetic locomotive organism capturing method is proposed. • The acoustic valve can restrict targets to a small region or separate locomotive targets from others. • The acoustic valve provides a new method for capturing or sorting micro swimmers.