Numerical analysis to determine the performance of different oocyte vitrification devices for cryopreservation.

Vitrification is widely used for cryopreservation of oocytes. The present study has built the theoretical models of four vitrification systems (micro-droplet, open pulled straws, quartz micro-capillary and cryotop), and performed numerical analysis to predict the cooling rates. The numerical analysis shows that the average cooling rate of the cryotop system was higher than those of other three systems between 298K and 100K. In addition, the effects of other process parameters on the cooling rate with the cryotop system were also investigated, including the thickness of the carrier, the volume of cryoprotectant agent, the temperature of cold source as well as the heat transfer coefficient, when plunging into liquid nitrogen.