Last Updated on November 28, 2023

Having a proper cryopreservation protocol is critical for many researchers that need to preserve and store biological samples. This is especially important for researchers in cell biology, regenerative medicine, and/or biobanking. The goal of a cryopreservation protocol is to preserve the quality and viability of biological samples by minimizing the formation of ice crystals, thereby reducing damage to the cell samples. This goal can be achieved using controlled-rate freezers. These freezers are essential tools for cryopreservation because they precisely control and lower the temperature of the sample to reduce damage. Innovations such as liquid nitrogen-free controlled-rate freezers developed by Strex are helping to make cryopreservation a more cost-effective, safe, and convenient process.

There are different types of controlled rate freezers, but they mainly fall into two categories: freezers that rely on liquid nitrogen and freezers that do not. Traditional freezers that use liquid nitrogen as a coolant are not only expensive and require regular maintenance, but they also pose potential contamination risks. Specifically, mycoplasma proliferates widely in liquid nitrogen and can be very hard to contain. This blog will explore the advantages of liquid nitrogen-free cell freezers and compare them to traditional options.

Advantages of liquid nitrogen-free controlled Rate Freezers:

Can be used in a clean room

Liquid nitrogen-free controlled-rate freezers are ideal for use in clean room environments due to their ability to eliminate the risk of contamination and safety hazards associated with traditional liquid nitrogen freezers. Liquid nitrogen can be a source of mycoplasma contamination if not handled properly, and on top of that, storage tanks can be prone to leaks, which can introduce contaminants into the freezer and samples.

Additionally, handling liquid nitrogen can pose several safety hazards, such as the risk of frostbite and burns. If the lab room is not well-ventilated, there is a risk of asphyxiation due to liquid nitrogen’s ability to evaporate into a gas and displace oxygen in the air. These are just some of the reasons why making appropriate safety precautions is paramount when using liquid nitrogen freezers, especially in clean rooms.

Using liquid nitrogen-free controlled-rate freezers in clean room environments minimizes these risks, providing a safer and more reliable solution for controlled-rate freezing. By eliminating the need for liquid nitrogen, these freezers ensure that the samples remain free from contaminants, and researchers can work safely without worrying about safety hazards. It is essential to use appropriate safety equipment, such as an oxygen monitor, to further minimize any risks associated with using these freezers.

Lower Costs

There are often logistical challenges associated with obtaining and storing sufficient quantities of liquid nitrogen. On top of that, liquid nitrogen is an expensive and scarce resource, making the cost of maintaining a liquid nitrogen freezer more expensive. In contrast, liquid nitrogen-free controlled-rate freezers do not require liquid nitrogen, making them more cost-effective in the long run.

Reduced Maintenance Requirements

Liquid nitrogen freezers require regular maintenance to ensure that they operate safely and effectively. This may include monitoring the temperature and liquid nitrogen levels, replacing worn or damaged parts, and cleaning the freezer to prevent contamination. Liquid nitrogen-free controlled-rate freezers require less maintenance, making them more convenient and time-efficient for researchers.


Unlike traditional liquid nitrogen freezers, Strex’s freezer is portable and does not require a dedicated liquid nitrogen supply. This makes it easier to use in a variety of settings, including fieldwork or remote research locations.

Disadvantages of liquid nitrogen-free controlled Rate Freezers:

Limited sample capacity

Some liquid nitrogen-free freezers have a limited capacity compared to ones that use liquid nitrogen, which can be a disadvantage if large numbers of samples need to be frozen at once.

Limited freeze velocity

The freezing rate has a physical limit of about -1C per minute if liquid nitrogen is not used. Though, it is important to note that not all cells are suitable for a faster freezing protocol for cryopreservation. The success of the freezing and thawing process can depend on various factors, such as cell type, cryoprotectant used, and the freezing protocol.

Fast freezing of certain tissues is a positive thing for research in certain contexts. For example, vitrification, or ‘snap freezing’, can be accomplished by submerging a sample in liquid nitrogen or an isopropanol bath in dry ice. In addition, fast cell freezing can be useful for certain types of experiments where cells need to be rapidly frozen to capture a specific cellular state or to prevent cell differentiation. For example, in single-cell sequencing experiments, researchers must rapidly freeze the cells to preserve their RNA content before analysis. Therefore, it is important to carefully consider the experimental requirements and optimize the freezing and thawing protocols accordingly.

A Comparison of Liquid Nitrogen and Liquid Nitrogen-free Cell Freezers for Research – Conclusion

Controlled rate freezers are essential tools in cell biology and regenerative medicine, for preserving and storing biological samples safely. They take the headache out of moving samples in and out of a clean room. It’s less expensive to maintain and easy to use. It can be used in regenerative medicine to freeze and store stem cells for later use in the treatment of various diseases.

Traditional options that use liquid nitrogen as a coolant have drawbacks, such as high costs, maintenance requirements, and potential contamination risks. Liquid nitrogen-free controlled-rate freezers offer advantages such as lower costs, reduced maintenance requirements, and minimized risk of contamination and safety hazards. Researchers who choose to use liquid nitrogen freezers should be aware of these factors and take appropriate measures to ensure their safety and the safety of their samples. They may also want to consider alternative options, such as liquid nitrogen-free freezers, which can offer similar precision and reliability without the drawbacks of liquid nitrogen use.

Find out more about our liquid nitrogen-free controlled-rate freezers and how they can help you in your research.