CONICET | Buscador de Institutos y Recursos Humanos

Microfluidics is starting to contribute significantlyin life science: biology [1], genetic,medicine, neuroscience. Indeed it hasalready addressed potentials applications in human reproductivemedicine. In particular, we have contributed to reach non-invasive spermrectifiers [2] and fertility analysis advances for future clinics applications[3]. In this work, wepresent experiments and modelling of human sperm cells under ultra-confinement(see figure below) as a key step to achieve efficient labs on a chip for human assistedreproductive technologies (ART). Our aim is to contribute with the advantagesof miniaturization and high-throughput analysis to the design of moreeconomical and efficient micro-devices, since this a social relevant problem atpresent when 70% of the couples should repeat the ART for a successfulpregnancy. We have fabricatedseveral designs of ultra flat micro-devices (h=25um < flagelar beating amplitude) for controllingcells directioning. Both its efficiency and the sperm motility close to the wallsare studied in detail. This is crucial to understand in microfluidics, wheresurface effects are dominant and not yet well investigated for spermatozoa. We have found originally that underultra-confinement an important part of the population recovers quickly almost100% of its velocity after arriving to lateral walls in contrast to itsbehaviour into larger devices. A minimalistic improved model with realparameters obtainsvery nice agreement between experiments and theory: the spermatic cells mean velocity and the orientationclose to the borders. Key-Words: microfluidics, spermatozoa, confinement, fertility, reproduction

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