Cell culture incubators have a rich history dating back many scientific generations. In fact, Louis Pasteur used a small crawl space under his staircase as an incubator! Modern incubators are built with design elements and features to meet both the demands of multiple users as well as a expanding range of cell culture types. Many factors must be considered in choosing an optimal, adaptable, and future proof piece of equipment.
First things first is an analysis of the types of cells and applications that are (and will be) required. This involves not just an assessment of current operations, but some foresight into future experiments and research areas. Questions may include: beyond microbial cultures, what type of eukaryotic cells will require the device down the road, will the lab be using stem cells or other types with complex requirements, or what range of personnel will be using the device and what special demands will these experiments have on the incubator?
The size of the incubator will depend both on the scale of usage as well as the space allocated for the device. Although the latter can sometimes be flexible, the former is not, and extra space may indeed serve the needs of future expansion in the scale and diversity of experiments. Some units are stackable, allowing one space to be used for multiple devices and applications. Other models can vary in dimensions, and some offer space saving designs to hug wall space and to fit in tight spaces -- a useful feature when faced with limited lab or dedicated cell culture space. It's important to consider not just the outer dimensions but the usable inner space as well. Many companies offer a rage of shelving options from standard to divided sectional to custom built for purpose in some cases. The ability to change shelving arrangements will help in expanding the usage of the unit, making room for components such as shakers.
The temperature control system is a very important consideration. Again, regardless of whether your current experiments are highly sensitive to temperature fluctuations, keep in mind the emerging needs of the lab and future-proof accordingly. Traditional cell culture incubators use a water jacket, or vessel of water, aimed at maintaining humidity and temperature stability. Although common, water jacketed incubators have been challenged by occasional contamination issues and the inability for fine control of environmental conditions. It's generally acknowledged in the field that when contamination issues arise, the first thing to change and sterilize is the water source. With the advancement of insulation technologies has come new approaches toward temperature control. Some incubators now use gel-jacketed (ceramic or otherwise) insulation to offer energy efficient solutions without the possible drawbacks of traditional setups.
The temperature probes are important in maintaining (or mapping) precise levels at different points in the incubation space. Moving from a single probe to multiple can tighten temperature differences several fold. The movement or circulation of the heated air is also important in speeding the recovery of temperature levels after the door is opened and a single or multiple fans serve this duty. An alternative system involves radiant heat produced by heating elements housed within the cabinet walls. Adjustable alarms assist in informing when a temperature threshold is exceeded, and these can come in different ranges and types as well.
The gas (CO2, O2, N2) control system is vitally important in the exposure of cell cultures to the specific environmental conditions needed for growth. Typical cell culture incubators are also CO2 incubators, and controlled CO2 is provided not only for atmospheric but for media purposes as well. When carbonate buffer is present in the media, the CO2 gas reacts to balance and maintain the pH. These media types often have pH indicator dyes which exhibit a color change when the media is consumed and requires changing. Modern incubators also have oxygen and nitrogen source inlets in order to emulate the precise conditions for cell growth. Some culture types may demand tight control of gas levels, and therefore, control, range, and uniformity should be considered accordingly.
Sterilization and decontamination are extremely important considerations when selecting a system suited for your present and future applications. The standard sterilization method is UV light, which has the benefit of safe and simple treatment with a short cycle. A downside is the possibility of contaminants persisting in areas evading exposure to the light. The option of HEPA filtration can trap small contaminants from air circulation thereby minimizing the risk and preventing the spread of contamination. Dry heat treatment, hot air (180 degrees Celsius) decontamination, is an effective method to eradicate any bacteria and spores, as well as remove condensation which can be a breading ground for these. Something to consider here is the cycle duration and unit downtime, as well as alarms and notifications. Another modern method involves hydrogen peroxide (H2O2) decontamination, in which the gas permeates every corner and crevice effectively killing nearly 100% (10^6 in some cases) of contaminants. The cycle and downtime should be considered here as well, but is typically in the 2-3 hour range.
Range, adaptability, and future-proof design lead the discussion on how the above features are traditionally built into incubator models, and how breakthrough technologies may add significant value and return on investment. Specific models are traditionally designed to match the general needs of the lab. For instance, should you need a straightforward water-jacketed device without the need for tight temperature tolerances and high functioning sterilization features, there is a more basic model available. In the same product line, there may be more complex models with a greater range of features and higher level stringency controls as well. The model-specific functionality is countered by the fact that, should your needs change down the road, an upgrade to an entirely new unit may be required.
New technologies include instrument platforms designed to match the evolving nature of today's research labs, often by circumventing the need for upgrading the entire device when operations change. Hardin Scientific embraces a modular concept with the T3-I7 Platinum Incubator, in which the incubator cabinet and base temperature control serve as the starting point. Temperature, gas, and sterilization upgrades can be added by attaching modular cubes by means of sterile quick connects. Beyond the flexibility and adaptability in custom configurations, the benefits include significant cost and time savings by minimizing downtime and limiting maintenance, repair, and replacement to only the affected module, leaving the core instrument intact and operational. Several additional modules can even kept on hand to plug and play as needed.
This technology fits the future-proof concept by avoiding the need to upgrade, repair, or replace entire instruments -- which many will agree is a massive drain on resources. Additional new technology features and accessories include: programmable notifications and alerts sent to smart devices, advanced data logging and archival, and real-time access to these data. These capabilities, while certainly not a requirement of all labs, are meant to support streamlined use and access, as well as compliance with regulatory guidelines such as ISO and GMP.
In summary, although traditional technologies have served the cell culture audience well, new technologies can add significant flexibility, value, and return on investment. Careful consideration of all of these factors should be performed in light of your current and future cell culture needs.