A Guide to Buying CO2 Incubators

Many life science and clinical research laboratories use CO₂ incubators, which provide a controlled and reliable in-vitro environment to ensure optimum growth of tissue cell culture.

An environment is also provided by the chamber where animal tissue cell cultures and gametes are stored and preserved for studies at or near body temperature. Humidity, sterility, temperature control, O₂ control, and CO₂ gas control are the parameters that play a key role in optimum growth condition.

These incubators are effectively operated and are capable of maintaining cells for long periods of time. As a result, research and other important activities associated with the cell and tissue culture held within can be easily performed.

However, the right incubator that suits specific requirements should be purchased to ensure that the cells are preserved in an environment, where they are suitably protected. In order to achieve this, a strong understanding of the various features and aspects of present incubators is required. This article serves as a buying guide that covers the main considerations that need to be taken into account when purchasing a CO₂ incubator.

Image credit: NuAire

Types of CO₂ incubators

From a larger perspective, the first important thing is to decide on is the type of incubator that will best meet the requirements of the clinical or research laboratory where it will be installed.

CO₂ incubators are available in two basic types – direct heat CO₂ incubator and water-jacketed CO₂ incubator. The aim of both these technologies is to establish and sustain a uniform temperature to ensure optimum cell growth.

Most incubators, are capable of maintaining a temperature of 37°C within around one-tenth of a degree. As a result, the internal chamber is surrounded by heating elements or water to obtain this uniform temperature. When it comes to humidity, temperature maintenance, ease of use or decontamination, etc., each technology comes with its own particular advantages and disadvantages.

Water-jacketed CO₂ incubators

Compared to air, water has a greater specific heat capacity and therefore it is traditionally used to regulate the temperature within laboratory incubators. In these incubators, a water jacket circulates around the outer side of the inner incubator shell, and through natural convection the water exchanges heat with the interior chamber.

This not only results in a uniform internal temperature but also provides a thermal buffer against the exterior air. During power outage, this thermal buffer can be particularly useful. Traditional incubators lack a large surrounding thermal mass produced by the heated water; a water-jacketed incubator can retain its heat approximately four to five times longer than these units. One further advantage is that the extra mass can reduce vibration, which would normally negatively impact the sensitive cell culture.

However, when water-jacketed incubators are filled, they tend to be extremely heavy when filled and therefore must be emptied before moving them. Once the incubators are moved, they can be easily refilled and restarted—but it could take as long as 24 hours before the unit can get back to a steady operating temperature.

Water jacket microbiological CO₂ Incubators from NuAire offer a consistent in-vitro growth environment by heating the walls of the chamber through water. Circulating inside the jacket walls, water creates a uniform temperature, ±0.2°C. If there is a large mass, the environment inside the chamber is less sensitive to external environmental variations.  The large mass also provides cabinet stability for growth of cells that are sensitive to vibrations.

Direct heat CO₂ incubators

The interior chamber in direct heat incubators [A] are covered in heating elements, which are usually packed in insulation layers. One or more heaters warm the interior chamber wall(s). Direct Heat incubators do not weight much and, since the inner chamber is directly heated, these units can be set up more quickly and the preferred temperature can also be achieved and recovered more quickly.

Image credit: NuAire

There are certain direct heat models that largely depend on natural convection to maintain a uniform distribution of heat within the chamber. There are also other models that keep a uniform heat distribution through mechanical assistance.

In the case of direct heat incubators, forced air can result in increased and unnecessary evaporation from cell cultures, thus presenting a major challenge. Fans can also generate vibrations and, in some cases, can produce a more favorable environment for bacteria, fungi, and other contaminants to thrive.

Yet, from a positive standpoint, direct heat incubators can decontaminate heat by using a dry-heat or moist-heat cycle, which is not present in water-jacketed models.

Direct Heat CO₂ incubators from NuAire have heating elements that are located on all six sides of the chamber, and provide a uniform in-vivo growth environment. The interior chamber temperature is stabilized by high-density insulation and therefore less energy is needed to maintain this temperature. Dual sterilization cycle, hypoxia and humidity control are special features through which the research requirements are fulfilled.

A number of factors should be taken into account before making a decision to buy a water jacketed or direct heat incubator.

Incubator location

The surrounding environment can affect the incubator’s performance and therefore the proposed location of the incubator should be taken into account when making a decision to purchase the incubator. In particular, incubators should never be placed under direct sunlight, close to autoclave, oven, or beneath air diffusers.

Instruments that are located in shakers and other similar incubators can also produce heat and can heat a well-insulated box beyond the set temperature. If this is a major problem, or if the incubator is not located in an air-conditioned space, the best choice would be to use a refrigeration capacity unit.

Usually, manufacturers test their incubators for both cold and hot spots and then follow up by publishing statistics related to temperature uniformity. It may also be useful to acquire test results when contemplating the final location of a unit.

Temperature control

Although the performance of the incubator can be affected by many physical factors, including location, stable temperature control is ensured through improved functionality and quality of incubators.

A more important consideration is to make sure that proper training is provided to those who use the incubator, especially with regard to keeping the door closed as much as possible. Strong user awareness should be present to reduce the possibility of temperature fluctuations caused by opening the incubator.

The interior temperature is disrupted whenever the incubator door is opened. As warm and cool air currents circulate inside, the temperature control system of the incubator should be able to bring back the internal temperature to the set level. Water jackets make incubators less sensitive to temperature fluctuations.

Image credit: NuAire

Humidity control

It is important to maintain the ideal humidification inside an incubator so that the cell cultures do not dry out. Humidity control also supports the key function of keeping an even osmotic cell pressure. Excessive and damaging evaporation can occur as a result of mismanaged airflow within the interior of the incubator.

Damage to cells and cell tissues that are stored, are also influenced by the type and amount of airflow that takes place inside the chamber and can be controlled with humidification controls.

NuAire decreases airflow inside its incubators in order to prevent the cell cultures from drying out. This is achieved by NuAire’s unique “Closed Loop HEPA Filtration System” [B] — a standard device on all NuAire CO₂ incubators.

The technology ensures that airflow is slowed to a single air exchange for every 30 minutes inside the inner chamber, which reduces desiccation or evaporation of the cell samples.

Image credit: NuAire

CO₂ control

It is essential to maintain a healthy CO₂ level inside the incubator as there is an interaction between CO₂ and the cell culture media’s buffering system to establish the pH of the media. An important choice to make to achieve CO₂ control is the type of CO₂ sensor integrated in the incubator.

Generally, traditional a thermal conductivity (TC) sensor is used by many incubators, but the latest type of infra-red (IR) sensor is usually more effective because it is not so highly sensitive to temperature and humidity in the chamber.

Contamination considerations

Preventing contamination of cell cultures is another key consideration in addition to the many factors that affect the maintenance of precise culture conditions, as there are many ways to introduce contaminants.

For example, contamination can take place when an open door brings in airborne contaminants, or when an unsterilized glove or hand comes into contact with the interior of the incubator. NuAire has developed a filtration system called Closed Loop HEPA Filtration System that can cut down the contamination caused by airborne species.

Majority of models employ sterilization cycles to clean the incubator’s interior surfaces. These sterilization cycles run at high heat and therefore the incubator should be emptied first.

The NU-5800 series from NuAire provides two types of sterilization cycles — +145°C dry and +95°C wet. The incubator also employs air pressure, which functions as another incubator defensive device, to guard cell cultures during the opening of doors.

Further, users should select incubator interiors that possess rounded corners. These will make it easier to clean by way of chemical disinfection, since no tight crevices are present in the incubator interiors where contaminants can grow.

Similarly, users should be aware of the incubator gasket that forms the seal around the internal door. The gasket is a region where humidity can develop, which if left unchecked, can lead to the growth of contamination.

Image credit: NuAire

A removable and easy-to-clean gasket should always be used. In case a v-gasket is used, users should remain aware of the flap direction. For instance, a flap pointing outwards towards the laboratory [C] will gather particles and prevent them from entering into the growth chamber, while a flap pointing inwards in an area for humidity to collect is the breeding ground for contamination.

An incubator whose interior surfaces contain copper is another method to achieve continuous protection. Copper is known to have antimicrobial properties, which can guard against the various contaminants caused by either the user or the base of culture plates.

In order to reduce the potential contamination of an incubator, NuAire now provides Copper surfaces to the incubator growth chamber and/or shelving.

NuAire develops incubators that are built on its popular biosafety cabinets, which also employ HEPA filtration to regulate contamination. NuAire integrates the HEPA filtration technology into its incubators, together with humidity controls that are specifically designed to preserve the right humidity level for the growth of cells. NuAire is renowned for reducing contamination. Since 1986, the company has been tracking contamination incidents in its incubators with less than 75 events.

Frequent cleaning of the incubator interior is the best way to reduce the possibility of contamination. This includes changing the water pan (if using) regularly and cleaning all nooks and corners such as brackets, shelves, etc.

Taking the next steps

In the end, making a decision on which incubator, or incubators, to buy is very crucial as it will affect the quality of work and outcomes at the specific facility. More awareness of various types of incubators and the level of considerations concerning capabilities and features will help those involved in the purchasing buying decision. Such users should also connect with those who are using the equipment on a daily basis.

A better understanding and input from those on “the front lines” in the clinical or laboratory setting will help purchase the right incubator to meet both present and future requirements. Also involving users in the buying decision can lay the basis for better adherence to effective operating protocols. The ultimate outcome will be incubators that improve the performance of the organization for many more years.

About NuAire

Quality and Service

For more than 40 years, NuAire has been committed to bringing you the highest-quality, most dependable laboratory products on the market.

We are universally recognized as one of the world's leading providers of reliable equipment for the most demanding environments, including Biological Safety Cabinets, CO2 Incubators,Laminar Air Flow workstations, Ultra Low Temperature Freezers, Centrifuges,Animal Transfer Stations, Pharmacy Compounding Isolators, Polypropylene Fume Hoods, Polypropylene Casework, and a variety of complementary products and systems.

You can depend on our products to feature brilliant but practical design, and we pay keen attention to every step of the production process, from fabrication to assembly to thorough testing. As a NuAire customer, you can also rely on us for outstanding value and dependable service - the cornerstones of our reputation as the leading provider of laboratory products internationally.

Committed to Your Success

At NuAire, we create our high-quality products with your success in mind. This means that if you purchase a piece of laboratory equipment from us, we want you to be completely happy while using it.

NuAire will work hand-in-hand with you in order to ensure that your experience using our product meets your standards, and if you encounter any issues or difficulties along the way, we'll help you work through them until you are 100% satisfied. Our philosophy is that we succeed only when you succeed - and we are committed to working hard to ensure you achieve your goals.

Made in America

At NuAire, you can depend on us for being a company that is "Made in America." Our Airflow Products, CO2 Incubators, and Polypropylene Products are manufactured at three locations in Minnesota.

With over 300,000 square feet of manufacturing space, including a state-of-the-art robotic sheet metal facility, NuAire is able to provide employment to 300 Minnesota families and 60 North American sales representatives, and our manufacturing labor is 100% American.

We also purchase our materials from over 500 American vendors, each operating principally in the United States. More than 60% of the raw materials, parts, and supplies for our products originates in the U.S., and an average of 20-30% of the stainless steel flats we use are made from recycled metal.

International Leader

While NuAire is an American company, we also have several international business partnerships, which allow us to better serve you, the global laboratory community. NuAire recently started manufacturing a line of Biological Safety Cabinets in China in order to supply products to the Asian markets via Techcomp, Ltd., a publicly traded Chinese company.

In 2014, NuAire founded an international partnership with Hitachi Koki in order to supply high performance centrifuges to the North American market. NuAire can now provide customers with the sales and service of Hitachi High Speed, Ultra, and Micro Ultracentrifuges.

With several other partnerships with a variety of European and Asian companies, we have sold over 100,000 biological safety cabinets to customers in 150 countries and have equipment located on all 7 continents.

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