Sperm selection is crucial to assisted reproduction, influencing the success rate of the treatment cycle and offspring health. However, in the current clinical sperm selection practices, bypassing almost all the natural selection barriers is a major concern. Here, we present a biomimicry microfluidic method, inspired by the anatomy of the female reproductive tract, that separates motile sperm based on their rheotaxis behavior to swim against the flow into low shear rate regions. The device includes micropocket geometries that recall the oval-shaped microstructures of the female fallopian tube to create shear protected zones for sperm separation. Clinical tests with human samples indicate that the device is capable of isolating viable and highly motile sperm based on their rheotaxis responses, resulting in a separation efficiency of 100%. The device presents an automated alternative for the current sperm selection practices in assisted reproduction.

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The sperm selection stage is what assisted reproductive technologies have in common and is crucial as it affects the success of the treatment cycle. The employment of microfluidic platforms for sperm selection has emerged showing promising results. In microfluidic platforms, sperm cells encounter micro‐confined environments meanwhile having contact with channel walls and surfaces. Modification of contact surfaces using nanoparticles leads to the alteration of surface characteristics which in turn affects sperm behavior especially motility which is an indicator for sperm health. In this article, we present the results of investigating the motility parameters of sperm cells in contact with surface‐modified glass substrates using nanodiamond particles. The results show that the sperm swimming velocities are significantly improved within the range of 12%–52% compared to the control surface (untreated). Reactive oxygen species production is also decreased by 14% justifying the increase in swimming speed. Taken together, bonding these modified surfaces to sperm selection microfluidic devices could enhance their efficiency and further improve their outcomes offering new solutions to patients facing infertility.

The employment of Nanotechnology as a valuable tool could be beneficial to patients and also offer new alternatives for Assisted Reproductive Technology (ART). Surface modification by nanoparticles leads to the alteration of surface characteristics (e.g. roughness, elasticity, and surface charge). These alterations affect sperm behavior especially its motility since sperms exhibit wall following behavior and surface accumulation. Moreover, surface modification is an attempt towards mimicking the complex in vivo environment of the female tract (highly folded and ciliated) with continually changing surface topology and also its functions. In this paper, we present the results of investigating the interactions between sperm cells and surface modified substrates using Nano diamond particles. A combinational and low-cost method was used for modification. The results show that the sperm motility parameters are significantly improved from 5 to 85%. Also, the results indicate that in optimized surface modification condition, the sperms swim faster and straighter and the surface facilitates the swimming due to the inherent characteristics of ND particles. Taken together, the replacement of normal with modified surfaces in fertility-aid microfluidic devices can enhance their efficiency and further improve their outcomes.