Lessons Direct

You’ve taken your first steps into a clean room where cell culture takes place. Let’s get you acquainted with one of the most important components of cell culture: the incubator.

Incubators: Where Cells Grow

A cell culture incubator is one of the most important pieces of equipment in a cell culture laboratory. Its job is to create a stable, controlled environment that closely mimics the conditions inside the human (or animal) body, allowing cells to grow, divide, and stay healthy outside of an organism.

Cells are sensitive to changes in their surroundings, so incubators help protect them from environmental stress. When working properly, an incubator quietly maintains the conditions your cells need—often for days or weeks at a time—while you focus on your experiments.

What Does an Incubator Do?

A cell culture incubator carefully controls several key environmental factors:

• Temperature
  Most mammalian cells are grown at 37 °C, which matches normal human body temperature.
• Carbon dioxide (CO₂)
  CO₂ levels (commonly 5%) help maintain the correct pH of the culture media when using bicarbonate-buffered systems.
• Humidity
  High humidity prevents evaporation of culture media, which could otherwise concentrate salts and harm cells.
• Sterility
  The incubator provides a clean, enclosed space to reduce exposure to contaminants like bacteria, fungi, and mold.

Together, these conditions create a safe “home” where cells can grow as naturally as possible.

Why Are Incubators So Important?

Without an incubator, cells would quickly experience stress or die due to temperature changes, pH shifts, or drying out. Incubators allow researchers to:

• Grow and maintain cell lines
• Perform experiments over extended periods
• Reproduce consistent conditions across experiments
• Minimize environmental variation that could affect results

In short, incubators help ensure both cell health and experimental reliability.

Main Parts of a Cell Culture Incubator

While designs vary by manufacturer, most incubators include the following key components:

1. Temperature Control System

• Heating elements and sensors maintain a constant internal temperature.
• Fans or air circulation systems help distribute heat evenly.

2. CO₂ Sensor and Control

• Monitors CO₂ concentration inside the chamber.
• Automatically adds CO₂ from a gas tank when levels drop below the set point.

3. Humidity System

• Typically a water pan at the bottom of the incubator.
• Keeps humidity high to reduce evaporation from culture vessels.

4. Interior Chamber

• Usually made of stainless steel or copper for easy cleaning and resistance to corrosion.
• Designed to support shelves and culture vessels.

5. Shelves and Racks

• Adjustable to accommodate flasks, plates, and other culture containers.
• Designed to allow proper airflow around cultures.

6. Door System

• An outer door for insulation and protection.
• Many incubators also have an inner glass door, allowing you to check cultures without fully opening the incubator and disturbing conditions.

7. Control Panel / Display

• Allows users to set and monitor temperature, CO₂, and alarms.
• Modern incubators often include digital displays and data logging.

8. Filtration and Sterility Features

• HEPA filters, copper interiors, or UV sterilization (model-dependent) help reduce contamination risk.

Everyday Care and Good Habits

Because incubators are shared and constantly in use, good habits matter:

• Open the door only when necessary and close it promptly
• Keep the interior clean and uncluttered
• Use sterile technique when placing or removing cultures
• Regularly check water pans and refill with sterile water as instructed
• Report alarms or unusual readings right away

Treat the incubator as a shared, sensitive environment—small actions can have big effects on everyone’s cultures.

Final Thoughts

Think of the incubator as a quiet partner in your experiments. It doesn’t ask for much attention, but it plays a critical role in keeping cells healthy and experiments successful. Understanding how it works—and how to use it properly—is one of the first steps toward becoming confident in cell culture work.

Questions for Consideration:

1. Your laboratory chore is to fill the laboratory incubators with sterile water. Your lab uses the MilliQ filtration system to sterilize water. You notice that there is an alarm on the MilliQ system about impurities in the water.
   
   Should you use the potentially impure water to fill the incubators? Why or why not?
   
   
2. You hear an alarm coming from an incubator. It reads “Low CO2”. What should you do?
   
   
3. Who is the emergency contact for the incubators in your laboratory?
   
   
4. How often should you check on the incubators in your laboratory?
   
   
5. You just received cells from a collaborator. They have not been tested for mycoplasma. What precautions should you take when incubating these cells?
   
   
6. One of the flasks in your incubator had a crack in the plastic, and the contents have spilled inside the incubator. How should you clean up this spill, and what protective equipment should you use?
   
   
7. What are the consequences of using an incubator that is incorrectly calibrated? For example, if the incubator reads 5% CO2 but the actual CO2 level is 9%, what can happen to the contents?
   
   
8. How do you calibrate the model of incubator that you use?
   
   
9. How often are your incubators calibrated and serviced?
   
   
10. Why are most incubators set to 37 degrees Celsius? What happens if an incubator runs too high or too low?