Abstract
Cryopreservation has been recognized as a powerful tool for long-term preservation of genetic resources. However, the outcomes of cryopreservation by different user groups often vary due to inconsistency in procedures and freezing equipment. Herein, we report on the feasibility of providing customizable sensing probes with three-dimensional (3-D) printing to monitor cryopreservation phenomena. The objectives were to: 1) introduce 3-D printing as a fabrication method for developing customizable probes to be used in cryogenic applications; 2) design and fabricate an example of a 3-D printed sensing probe and multiplexer capable of detecting phase-change phenomena based on quantitative data regarding sample electrical resistance and temperature, and 3) demonstrate the sensing platform in cryopreservation conditions and in combination with a custom-made 3-D printed freezing device. The sensing probe developed was designed to fit within standard 0.5-ml French straws. Phase-transition phenomena were detected by analyzing electrical resistance changes. The quantitative data from this device in conjugation with a 3-D printed freezer rack provided cryopreservation capability with high reproducibility and offered an alternative to expensive programmable freezers. The use of 3-D printing provided flexibility to develop new sensing probes or modify existing designs based on specific needs. After initial prototyping, fabrication, and testing of 3-D printed sensing probes, particularly useful designs can lead to the reduction of variation in performing standardized cryopreservation protocols.