Enhancement of zebrafish sperm activation through microfluidic mixing induced by aquatic microrobots

The activation of zebrafish sperm is essential for advancing vertebrate research, including studies in germplasm physiology and cryopreservation. In this study, a magnetic microrobot-based micromixer is developed to maximize zebrafish sperm activation through uniform micromixing and precise hydrodynamic control. Three distinct configurations of the microfluidic channel, labeled Design I, II, and III, are proposed and employed to activate zebrafish sperm cells. These configurations are distinguished by the number of microrobots utilized and their specific placement within the microfluidic channel. The fluid shear rate induced by the microrobot’s rotational motion is quantified to be 0.2 s⁻¹, falling within the lower range conducive to sperm activation. Meanwhile, zebrafish sperm activation percentage is observed to reach 88% within 10 s in an individual experiment. Additionally, the dynamics of sperm motility parameters, including VSL (straight-line velocity), VCL (curvilinear velocity), and LIN (linearity, VSL/VCL), are quantified to verify these results. The LIN value is observed to be 0.91 for Design III at the actuation time period of 10 s, indicating that the activated sperms are highly efficient and progressively motile. This study underscores the efficacy of microrobotic technologies in live cell manipulation, establishing a promising approach for future research.