Guidance and Self‐Sorting of Active Swimmers: 3D Periodic Arrays Increase Persistence Length of Human Sperm Selecting for the Fittest

Abstract

Male infertility is a reproductive disease, and existing clinical solutions for this condition often involve long and cumbersome sperm sorting methods, including preprocessing and centrifugation‐based steps. These methods also fall short when sorting for sperm free of reactive oxygen species, DNA damage, and epigenetic aberrations. Although several microfluidic platforms exist, they suffer from structural complexities, i.e., pumps or chemoattractants, setting insurmountable barriers to clinical adoption. Inspired by the natural filter‐like capabilities of the female reproductive tract for sperm selection, a model‐driven design, featuring pillar arrays that efficiently and noninvasively isolate highly motile and morphologically normal sperm, with lower epigenetic global methylation, from raw semen, is presented. The Simple Periodic ARray for Trapping And isolatioN (SPARTAN) created here modulates the directional persistence of sperm, increasing the spatial separation between progressive and nonprogressive motile sperm populations within an unprecedentedly short 10 min assay time. With over 99% motility of sorted sperm, a 5‐fold improvement in morphology, 3‐fold increase in nuclear maturity, and 2–4‐fold enhancement in DNA integrity, SPARTAN offers to standardize sperm selection while eliminating operator‐to‐operator variations, centrifugation, and flow. SPARTAN can also be applied in other areas, including conservation ecology, breeding of farm animals, and design of flagellar microrobots for diagnostics.

Sperm Cell Driven Microrobots—Emerging Opportunities and Challenges for Biologically Inspired Robotic Design

“…An example of advances to overcome some of these challenges is the Simple Periodic ARray for Trapping and isolation (SPARTAN) [104] (Figure 7), a microfluidic sperm-sorting device. In this process, a simple periodic array device is used to sort out individual sperm cells.…”

“…This is a cause for concern because we need sperm cells that are highly motile, to be as efficient as possible for actuation. While there is considerable interest in this particular field [94][95][96][97][98][99][100][101][102][103][104], a standardized method and protocol is highly crucial and is the need of the hour.…”

Progressive Sperm Separation Using Parallelized, High-Throughput, Microchamber-based Microfluidics

“…In addition, these methods require a stringent skill set, lack standardized procedures, and prone to human errors (1), not to mention that they unfavorably are time consuming. However, new technologies with minimal perturbation, such as microfluidics, have been extensively explored and considered as promising remedies for the flaws associated with the conventional methods (2,7,(11)(12)(13)(14)(15).…”

Density gradient centrifugation and swim-up for ICSI: useful, unsafe, or just unsuitable?

“…Comparing spermatozoa migration through channels of different lengths, Tasoglu et al [11] determined that a 2-cm migration is enough to obtain functional human spermatozoa, as sperm exhaustion has been considered an important principle in microfluidic sperm selection. In this scenario, a microfluidic device for clinical use was developed based on experimental data [12]. Briefly, the spermatozoa must actively swim from the inlet reservoir through the main channel to the outlet reservoir to be collected.…”