Assisted reproductive technologies on-chip: the application of microfluidics and optics to sperm assessment and sorting.

CONTEXT: Semen evaluation plays a key role in the success of assisted reproductive technologies (ART) as it allows high-quality spermatozoa to be selected. Conventional analysis methods are widely performed despite drawbacks, including subjectivity, potential sample damage, high costs and the need for specialised personnel, highlighting the demand for standardised, accessible and minimally invasive approaches.

AIMS: This review describes the potential of microfluidics and optical trapping (OT) as alternative approaches for semen assessment and selection, exploring their possible combination and integration into ART workflows.

METHODS

A literature review was conducted to describe in vitro assessment of spermatozoa and explore conventional methods for selection, separation and sorting. Microfluidics and OT were introduced from basic concepts to applications in biology. Their application to assisted reproduction was then examined, focusing on sperm sorting, assessment and IVF and intracytoplasmic sperm injection techniques.

KEY

RESULTS

Microfluidic systems, exploiting laminar flow within microchannels, represent a non-invasive approach to sperm selection. They enable motile spermatozoa to be separated from immotile or abnormal spermatozoa while reducing centrifugation-related phenomena such as mechanical stress and DNA fragmentation. OT allows precise manipulation of spermatozoa and quantitative investigation of sperm motility, swimming force and cellular behaviour. The integrated use of Raman spectroscopy and fluorescence imaging allows cellular activity assessment.

CONCLUSIONS

Microfluidics and OT provide complementary approaches for sperm assessment and sorting, integrating non-invasive selection strategies with single-cell manipulation and analysis.

IMPLICATIONS: The integration of these approaches into a single optofluidic device may support incorporation into ART workflows, promoting improved semen selection and analysis.