On-Chip Three-dimension Cell Rotation Using Whirling Flows Generated by Oscillating Asymmetrical Microstructures

The capability to precisely rotate the cells and other microscale objects is invaluable in biomedicine, bioengineering, and biophysics. We propose a novel on-chip three-dimension (3D) cell rotation method using whirling flows generated by oscillating asymmetrical microstructures. In an acoustic field excited by the vibration of a piezoelectric transducer, two different modes of microvortices are generated around our custom-designed microstructures that are utilized to precisely achieve in-plane and out-of-plane rotational manipulation of microparticles and cells. The rotation mechanism is studied and verified using numerical simulations. We also investigate the effect of various parameters on the acoustically induced flows such as the frequency, the driving voltage and the distance from the microstructure tip to the oocyte center, thus indicating the rotational speed can be effectively tuned on demand for single-cell studies. Finally, by observing the maturation stages of M2 after excluding the first polar body of operated oocytes, the proposed method is proved noninvasive. Comparing with the conventional works, our acoustofluidic cell rotation approach is simple-to-fabricate and easy-to-operate, thereby allowing rotations irrespective of the physical properties of the specimen under investigation.