SPARTAN (Simple Periodic ARray for Trapping And isolatioN) for selecting motile and morphologically normal sperm. a) Schematic diagram of the microfluidic pillar array and an illustration of pillar dimensions. b) Photograph of the microfluidic device (scale bar: 10 mm). c) FESEM image of the 30 × 26 µm periodic pillar array (scale bar: 50 µm), and a close-up FESEM image (inset) showing micropillars in detail (scale bar: 20 µm). d) Percentage of motile sperm at different pillar periodicities is plotted. Data are shown as average ± standard deviation. The brackets represent a statistically significant difference compared with the groups using one-way ANOVA with Tukey’s posthoc test for multiple comparisons (N = 3, p < 0.05). e,f) Simulated trajectories of (n = 100) normal morphology sperm in channels with 18 × 26 µm (left) and 26 × 26 µm (right) array periodicities. g) Simulated trajectories for sperm with abnormal morphology in a channel with 30 × 26 µm array periodicity. Trajectories of sperm with a bent neck (0.1π radians) and a larger head (×2 normal) are shown in red and blue, respectively.
Guidance and Self-Sorting of Active Swimmers: 3D Periodic Arrays Increase Persistence Length of Human Sperm Selecting for the Fittest
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.