| abstract |
Successful cryopreservation by the vitrification method depends on high chilling speed. Practitioners of vitrification prefer to use liquid nitrogen as the chilling cryogen due to its inherent safety and low cost. Plunging vitrification cryocontainers in to a quiescent pool of liquid nitrogen invariably results in a chilling rate less than the theoretical potential. The shortfall is attributed to the well-known Leidenfrost effect. The purpose of this invention it to provide improve chilling rates during vitrification using liquid nitrogen. One feature of this invention is a contacting device that invokes convective heat transfer principles to increase chilling speed. In another feature of this invention, cryogen velocity is derived from a self-pressurized dewar containing a saturated cryogen. The self-pressurization is achieved by ambient heating of the dewar's contents. In another embodiment, a sub-cooled cryogen, such as propane, is used in tandem with a saturated cryogen, such as LN2, in a self-pressurized dewar. |