A method to prevent clogging and clustering in microfluidic systems using microbubble streaming.

This paper presents an innovative strategy to address the issues of clogging and cluster-related challenges in microchannels within microfluidic devices. Leveraging three-dimensional (3D) microbubble streaming as a dynamic solution, our approach involves the controlled activation of microbubbles near channel constrictions, inducing microstreaming with distinctive features. This microstreaming, characterized by a high non-uniform 3D gradient and significant shear stress, effectively inhibits arch formation at constrictions and disintegrates particle clusters, demonstrating real-time prevention of clogging incidents and blockages. This study includes experimental validation of the anti-clogging technique, a detailed examination of microstreaming phenomena, and their effects on clogging and clustering issues. It also incorporates statistical analyses performed in various scenarios to verify the method's effectiveness and adaptability. Moreover, a versatile control system has been designed that operates in event-triggered, continuous, or periodic modes, which suits different lab-on-a-chip applications and improves the overall functionality of microfluidic systems.

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

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.