Master of Science (MS)
Biological and Agricultural Engineering
Lack of standardization of terminology and protocols, combined with limited access to freezing equipment due to cost constraints and lack of portability, has created a need for inexpensive cryopreservation devices. Distribution of standardized methods of freezing cells would enable the development and adoption of standards on materials and protocols. Some cryopreservation methods are limited by the amount of cells available and the toxicity of certain cryopreservation agents. These studies would benefit from the ability to cool individual samples. All commercially available and proposed cooling devices operate by cooling batches of samples at the same time. The cryopreservation conveyor was designed to provide a portable, inexpensive, low-throughput means for continuously freezing French cryopreservation straws. The device consists of a 3-D printed conveyor driven by a stepper motor that operates above a reservoir of liquid nitrogen within a polystyrene cooling chamber. The height and speed of the conveyor can be adjusted to provide customizable freezing parameters such as cooling rates (6 to 40 °C/min) and plunge temperature (-30 to -160 °C). Three-dimensional printing is a particularly appropriate means of fabricating the device, as 3-D printed polylactide structures can be created that have low density while still maintaining structural integrity in cryogenic conditions. The cooling rates produced by the conveyor had a standard deviation of less than 4 °C/min. A comparison of freezing koi (Cyprinus carpio) sperm on the con-veyor and a commercially available controlled-rate freezer shows similar post-thaw motility. These results suggest that the conveyor device could meet the aforementioned needs to aid in standardization and reproducibility of cryopreservation efforts.
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Eskridge, Melissa Kaye, "3-D Printed Conveyor for Continuous-Mode Cryopreservation of Individual Samples" (2016). LSU Master's Theses. 4551.