Heat transfer analysis of a self-designed cooling rate controllable device and its application for cryopreservation of biological cells

Cryopreservation is the technique to preserve the biosamples at extremely low temperature. The optimal cooling rate is an important factor influencing the survival of biological samples during cryopreservation. In this study, we established a combined experimental-modeling approach for high precision prediction of the temperature distribution during cryopreservation of biosamples by simple passive cooling rate control device (PCD) instead of conventional liquid nitrogen (LNF) method that leads to uncontrolled rewarming and cell destruction. Moreover, the PCD method does not require any consumption of liquid nitrogen with minimum invigilation of the labor whereas the LNF approach needs this support. In our experiment, we have used PCD to cryopreserve the natural killer T (NKT) cells and also simulated the model with actual device dimensions and its properties. We systematically evaluate our results of the PCD method with the conventional LNF method by acquiring the viability and functions of the NKT cells after the cryopreservation. The PCD method proposes a high-efficiency, cost-effective, robust, and minimal labor approach for cryopreservation of the biosamples for preservation and transportation.