OBJECTIVETo establish a new method for sperm sorting by imitating the physiological process of sperm-cervical mucus interaction on the microfluidic chip.

METHODSWe designed a microfluidic chip to imitate the physiological process of natural sperm sorting in the microchannel based on the interaction between sperm and cervical mucus, and obtained motile sperm after the interaction. Meanwhile, we established an integrated real-time sperm detection reservoir on this chip to determine sperm parameters using the computer-assisted sperm analysis system. We analyzed 30 samples using both microfluidic and swim-up methods, and compared the results with those obtained before sorting.

RESULTSThe rate of grade a + b sperm, the rate of morphologically normal sperm, straight-line velocity (VSL), average path velocity (VAP) and straightness (STR) were (29.78 +/- 11.24)%, (8.00 +/- 5.19)%, (18.89 +/- 4.90) microm/s, (26.84 +/- 5.13) microm/s and (70.15 +/- 7.61)%, respectively, before sorting, (71.65 +/- 11.18)%, (14.95 +/- 6.79)%, (24.14 +/- 5.95) microm/s, (32.61 +/- 6.36) microm/s and (73.87 +/- 9.34)%, respectively, after swim-up sorting, and (92.37 +/- 6.33)%, (23.33 +/- 7.67)%, (34.03 +/- 16.78) microm/s, (38.73 +/- 16.40) microm/s and (84.91 +/- 12.56)%, respectively, after sorting on the microfluidic chip. The sperm parameters obtained before sorting showed statistically significant differences from those obtained on the chip (P < 0.01) and by the swim-up method (P < 0.05).

CONCLUSIONImitation of the physiological interaction between sperm and cervical mucus on the microfluidic chip helped the realization of both the natural sorting and real-time analysis of sperm. The quality of the sperm sorted on the microfluidic chip is significantly better than that of the sperm before sorting and sorted by the swim-up method. This has prepared the ground for imitating the fertilization process under the physiological condition on the microfluidic chip.