Cooling rate is the key factor that determines the cryopreserving effect of cells

which has much to do with the forms and the usages of freezing carrier. In this study

digital oscilloscopes and type T thermocouple of 80 μm diameter were employed to establish a high speed temperature measurement system. The cooling rates of cells were measured by using a new type of enclosed oocyte freezing carrier in different ways of being inserted from air to liquid nitrogen. The results showed that the cooling of freezing carrier is mainly fulfilled via heat convection; When the carriers were horizontally placed

the cooling rate of carrier when the air hole was perpendicular to liquid nitrogen is higher than that when the air hole was tangent to liquid nitrogen; when the freezing carrier was directly inserted into liquid nitrogen

the cooling rate of carrier was higher than that when the freezing carrier was inserted into liquid nitrogen and then swayed; when the freezing carrier was placed downwards

the cooling rate of carrier was higher than that vertically or horizontally placed. Based on the results mentioned above

when the carrier was directly inserted into liquid nitrogen downwards

the cooling rate could reach as high as 54572 ± 1338 K/min

which is the highest and favorable to verification of oocytes.