Comparison of Varied Microfluidic Ratchet Designs on Sperm Sorting and Quality in Low-Quality Samples

Document Type : Original Article

Authors

1 Department of Chemical Engineering, Faculty of Engineering, Shahid Bahonar University of Kerman, Kerman, Iran

2 Afzalipour Clinical Center for Infertility, Afzalipour Hospital, Kerman University of Medical Sciences, Kerman, Iran

Abstract

Infertility affects approximately 17% of adults worldwide, with male factors contributing to 20–40% of cases. Conventional sperm selection methods, such as density gradient centrifugation and swim-up, can cause DNA damage via reactive oxygen species and mechanical stress, limiting their use in assisted reproductive technologies (ART), including intracytoplasmic sperm injection. Microfluidic systems provide a gentler alternative by exploiting sperm motility and morphology. Using polymethyl methacrylate sheets laser-engraved to create asymmetric ratchet geometries, four designs were evaluated at flow rates of 0.034 mL/min and 0.017 mL/min. Semen samples from patients with low sperm quality were injected, and output fractions were assessed for concentration, motility, morphology, and the sperm retrieval index (SRI), a composite metric normalized to World Health Organization standards. The results showed consistent improvements, with optimal designs yielding up to a fourfold increase in sperm concentration (e.g., from 10 to 40 million/mL) and over 20-fold SRI enhancement, particularly at the lower flow rate, which minimized shear stress and promoted rheotactic trapping of motile sperm. These findings suggest that ratchet microchannels offer a simple and effective approach for sperm enrichment and improving ART outcomes without the need for centrifugation.

Keywords

Main Subjects

References

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Veterinary and Comparative Biomedical Research
Volume 3, Issue 2
June 2026
Pages 45-60

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