Tech Compare: Lab Freezers

Freezers are used within many different types of laboratories to ensure the safety of valuable samples, from enzymes to pharmaceutical products, DNA, blood, bone material and more. If you’re in the market for a new freezer, comparing this ubiquitous tool across manufacturers and solutions starts with one critical element: operating temperature.

How cold should you go?

Different sample types require different temperatures and storage requirements to ensure product stability and usability. For example, a flu shot at a pediatric office only needs -20◦C for a short amount of time before it will be administered. Meanwhile, forensic laboratories need to ensure DNA and blood samples are stored for decades in some cases.

Thus, before you zero in on other features of lab freezers, the first step is to determine which type of freezer best suites your sample workload.

Manual vs. automated retrieval

Maintaining the integrity of stored samples in any collection is paramount. That, however, can be difficult when storing a large number of samples or sharing a freezer in a high traffic area. For example, a vaccine stored at the back of the freezer and one stored in the middle of the rack should be the same temperature, and not fluctuate more than ±1.5°K from the initial set point. If the freezer is being opened many times during the day, or even left open for a period of time, this could disrupt the materials stored at the front of the freezer.

Traditionally, tubes have been stored in boxes of samples. When a researcher needs a specific tube, they manually extract the entire rack to find the needed sample. Again, depending on the frequency of manual rack removal, as well as the time allotted to the practice, this could negatively alter the temperature of the remaining tubes in the rack—making them warmer than their counterparts in the back of the freezer that have not been extracted in the last 24 hours. This also subjects the samples to multiple freeze/thawing cycles.

That is why some researchers prefer freezers with automated sample storage and removal. This offers rapid “cherry picking” of samples, delivering only the requested samples while avoiding the disruption of non-required tubes. Automated storage and retrieval can cherry pick individual tubes, as well as custom rack combinations, reducing manual handling and labor time.

Automated storage and retrieval technology can also interface with a laboratory’s LIMS, if available. In this case, the use of barcoded tubes ensures sample information and data is logged accurately. With the information logged, the cherry picking of sample sets based on different criteria—such as age, sample type, or blood chemistry—can be automated.

Design structure

Generally, there are three types of freezers: upright, undercounter and chest.

Upright freezers are the most common, suitable for a variety of applications, laboratories and facilities. Due to their vertical design, these freezers take up minimal floor space, yet store maximum qualities of samples and other materials. Upright freezers typically have interior shelving units that make sample organization easy and effective. Small upright freezers are ideal for practices with limited space or the need to store a small capacity of samples, while large upright freezers are suitable for big research institutions and hospitals.   

Upright freezers are also popular due to their excellent temperature uniformity, ability to promote exposure of all lab samples to the same conditions, and quick recovery time after environmental exposure.

If floor space is even tighter, lab managers should consider undercounter freezers, which utilize cabinet space instead of floor space. Beside space, undercounter freezers are very similar to upright freezers, although their installation cost is higher due to their location.

Chest freezers are ideal for laboratories and facilities that need to store many items in a single device. They open from the top rather than the front, like most other freezers. They also do not have shelving in their interior. This option is best for long-term storage of samples.

Regardless of overall design, consider a freezer with a modular structure that would allow your lab to expand as needed, offering flexibility and futureproofing. For example, the modular structure of SPT LabTech’s compact allows laboratories to start small now but expand later. The modules can be located at separate locations but remotely connected to create a network that scales to meet your laboratory’s needs.

Temperature monitoring

If the most critical element is operating temperature when purchasing a new laboratory freezer, then it stands to reason that ensuring that temperature does not fluctuate is also paramount.

Nowadays, most freezers come with sophisticated alarming systems that signal when a freezer is out of temperature range due to, for example, the door left ajar or a power failure. Lab freezers, whether ultra-low-86⁰C or units freezing to -25, -30 or -40⁰C, should have high-low temperature alarming systems plus remote alarm contacts that can be connected to alarms that sound elsewhere in the research facility.

For units not equipped with a built-in alarming system, or for labs that want to invest in a backup method, there are alternatives. Data loggers, for example, offer continuous monitoring of freezer temperatures and can alarm when temperatures are out of specification. They can also be set up to alarm for out-of-range temperatures, although they do not provide remote notification. The data saved by a data logger can typically be downloaded and stored using a USB memory device, or they can be connected to a local area network.

Wireless Internet of Things (IoT) monitoring is also an option. In this case, each monitoring device connects directly to the internet, and to a data portal in the cloud. With the portal, the user can monitor equipment in real-time, as well as receive immediate email or SMS alerts for out of spec temperatures. Data is stored securely in the cloud and is simple to access for regulatory requirements. While this method boasts superior monitoring and remote alarms, initial setup costs are higher than other methods.