Micro-particle aggregation using vortices induced by vibration of a piezoelectric cantilever beam-probe structure.

Large-scale nondestructive aggregation of micro-particles is essential for cell detection, microplastics removal and micro- and nano pharmaceuticals. To achieve this goal, this work proposes a method by creating a vortex region in the fluid field using low-frequency oscillation of a piezoelectric cantilever beam probe structure. Vibration of the probe agitates the liquid, creating a horseshoe-shaped vortex in the fluid field. This facilitates the movement of micro-particles and traps them. Using polystyrene microspheres with a diameter of 20 µm and pollen (20–40 µm) as aggregated objects, particle agglomeration tests and flow field PIV tests are performed. Experimental results confirm that the designed structure has the best performance with a driving voltage of 100 V and a driving frequency of 72 Hz. The maximum aggregation area of polystyrene and pollen is 106956 µm2 and 234750 µm2. There are symmetrical large vortices regions on both sides of the probe and small vortices zero vorticity near the free end of the probe. It is also confirmed that small vortices are the root cause of microparticle aggregation. The aggregation method proposed in this study has advantages of low cost, non-selectivity of characteristics for controlled samples, large manipulation area and low power consumption (0.42 W). [Display omitted] • The aggregation of microparticles is realized by using the vortex of the flow field. • The edge-based image segmentation is conducted to character the aggregation results of microparticles. • The PIV experiment revealed the distribution of vortex in the flow field when the microparticles are aggregated. [ABSTRACT FROM AUTHOR]