Enhanced particle separation through ultrasonically-induced microbubble streaming for automated size-selective...

In this study, we present an automated method for achieving Size-Selective Particle Depletion in microchannels. This technique is notable for its label-free, sheath-free, and cost-effective attributes. It combines continuous Poiseuille flow with microbubble streaming to enable the manipulation of particles in an automatic or semi-automatic manner at periodic intervals. Larger particles are retained in proximity to the microbubble, with the option for subsequent eviction through a designated waste exit or their accumulation within a collection chamber for future analysis or manipulation. Unlike many conventional methods, our approach keeps the target particles in the vortices near the microbubble while the primary fluid flows continuously through the microchannel. Subsequently, these particles are ejected in just a few milliseconds, preserving the primary fluid and significantly reducing fluid wastage. We conducted an analysis covering multiple critical facets of the study. This included a rigorous statistical examination, flow characterization using volumetric micro PTV, high-frequency micro PTV for observing flow field transitions, evaluating the system's particle trapping capabilities across different sizes with a proprietary algorithm, and investigating the z-axis distribution of both incoming and escaped particles using volumetric micro PTV. The invaluable insights gleaned from this data played a pivotal role in refining the system and optimizing its operational parameters to achieve peak efficiency across various conditions, encompassing varying particle sizes, flow rates, and seeding densities.