Microfluidic innovations driving the future of sperm motility and sex sorting techniques

Sperm sorting plays a pivotal role in assisted reproductive technologies (ART), ensuring the selection of functionally competent spermatozoa for enhanced fertilization, implantation, and pregnancy outcomes. Traditional approaches such as swim-up, density gradient centrifugation, and simple wash techniques, though widely applied, are often limited by mechanical stress, reduced efficiency, and compromised sperm integrity. Parallel efforts in sex-based sorting using gradients, surface charge, or immunological strategies have also faced challenges, including high cost, DNA damage, and limited clinical translation. Recent advances in microfluidics have emerged as a game-changer in ART, offering biomimetic micro-environments that replicate sperm guidance mechanisms, including chemotaxis, thermotaxis, and rheotaxis, while enabling precise motility-based sorting with minimal manipulation. Microfluidic platforms not only improve the isolation of morphologically superior and genetically intact spermatozoa but also provide scalable, rapid, and less invasive alternatives to conventional methods. Here, we review the evolution of sperm sex and motility sorting technologies, highlight recent progress in microfluidic platforms, and consider their implications for livestock breeding. Innovations in microfluidic device design, including microchannel geometries, integrated flow cytometry, photonic separation, and dielectrophoresis, demonstrate transformative potential for sex sorting. Finally, we discuss future directions, including the integration of automation, biosensing, and artificial intelligence, that could establish next-generation platforms for precision sperm selection in reproductive medicine and biotechnology.