Introduction 

The CO2 incubator provides an optimal environment for cell and tissue culture growth. It maintains a constant temperature and high humidity with CO2 control. It also prevents cell contamination since the incubator is sealed off from the outside environment. The CO2 incubator maintains a 7.4 pH, and has a relative temperature range of +5 ~ 60 ℃, an ambient temperature of 18~30℃, relative humidity of ≤80%, and a CO2 range of 0~20%. 

Conduct science offers a CO2 incubator of three-volume capacities (50L, 80L, and 160L). It includes an air jacket with a 90℃ steam sterilization function. A major advantage of this incubator is that the data can be saved in real-time since it is equipped with a USB port and LCD touch screen. The temperature, CO2 concentration, and run-time are also displayed on the LCD screen. The CO2 concentration can be accurately maintained with the incubator’s high-quality infrared sensor. The incubator is equipped with 2 shelves, which are adjustable. The shelves also contain holes, allowing the temperature inside the incubator to be uniformly spread. The incubator also includes a bottom chamber that holds up to three liters of water to ensure high humidity. 

Apparatus and Equipment 

The CO2 incubator comprises a chamber that maintains the desired temperature and humidity. The external part of the incubator is made of cold-rolled steel with painting, while the internal portion is made of stainless steel. It includes an inner door and an external door.

Heating inside the incubator is provided by an air jacket. Sterilization is performed with a 90℃ moist heat decontamination function (95%≤humidity≤99%RH). The incubator can control the temperature within the range of +5 ~ 60 ℃. It allows a temperature fluctuation of ≤ ±0.2℃ (at 37℃) and has a temperature uniformity of ≤ ±0.3 ℃ (at 37℃). The timing of the incubation period can be set at 999h, or incubation can be performed continuously. The incubator is equipped with several alarms, including an audible and visual alarm, over-temperature alarm, and CO2 concentration alarm. The CO2 range is between  0~20%, which is controlled with an infrared sensor. The CO2 control resolution is 0.1%. The incubator includes a water reservoir at its bottom which ensures high humidity of 90%≤relative humidity≤99%. It has an ambient temperature of 18~30℃ and relative humidity of ≤80%. 

The internal part of the incubator measures 338×392×442 mm while the external measures 575×632×830 mm. It comes in three-volume capacities (50L, 80L, and 160L). Its weight depends on the size of the chamber. The 50L capacity weighs 85 kg,  80L weighs 108 kg, and 160L weighs 147 kg. 

Applications 

The CO2 incubator is used in several applications for various medical and pharmaceutical industries. It is used in tissue engineering, in vitro fertilization, medical research, diagnostics, and developing biosensors. 

• In vitro fertilization (IVF) –

The CO2 incubator is commonly used to incubate oocytes and sperm. The oocytes and sperm are placed in a petri dish where they fertilize and develop in the incubator for a few days before being transplanted into a uterus. It provides the optimal conditions for the growth of the embryos.

In a study conducted by Iwayama, Ishikawa, Ohsumi, and Fukui (2005), they compared a portable CO2 incubator and a standard CO2 incubator in their effectiveness for in vitro maturation (IVM) of minke whale, bovine, and porcine oocytes. No significant differences were observed in the maturation of the oocytes between the standard and portable CO2 incubators. 

Another study conducted by Nabavi, Todehdehghan, and Shiravi (2013) used a CO2 incubator to assess the effect of caffeine on mouse sperm motility, vitality, and fertilization rate in T6 and M16 media. The sperm were added to the oocytes in the media with or without caffeine. They were then incubated in the CO2 incubator for 24 hours. The results from the study revealed that when caffeine was added to the T6 medium, enhanced fertilization, motility, and vitality of the sperm were observed. 

• Tissue engineering 

CO2 incubators are used to cultivate cell and tissue cultures for tissue-engineered products. These products are used to develop novel treatments for various diseases, including malignant tumors. 

In a study conducted by Domansky et al. (2010) they developed a bioreactor that maintains 3D tissue cultures under continuous perfusion. They also integrated several bioreactors into an array using a multiwell plate format. They perfused the multiwell plate inside a humidified 5% CO2 incubator maintained at 37°C.

A CO2 incubator was also used in a study by Tripathi and Basu (2012), who investigated a porous hydroxyapatite scaffold for bone tissue engineering. The CO2 incubator was used to incubate the tissue culture plates. 

• Diagnostics 

The CO2 incubator is used for various processes in the diagnostic analysis of pathogens that involve examining cell cultures. The incubators are used in the processes of thawing, transferring the cells, infecting the cell line, and dyeing the cell cultures. 

In a study conducted by Zimmerman et al. (2010), they investigated the stability of porcine reproductive and respiratory syndrome virus (PRRSV) at various temperatures. The CO2 incubator was used to incubate the samples in roller bottles comprising minimal essential medium (MEM) and growth medium supplement.

Precautions 

• Keep the CO2 incubator out of direct sunlight, air-conditioning ducts, close to vents, or the exhaust of heat-or cold-generating equipment, since these can affect the chamber conditions.
• Avoid placing the incubator directly on the floor. 
• Ensure the area outside the incubator does not have dust or dirt since these can enter the chamber when it opens. 
• Clean and disinfect the incubator’s interior before use. 
• When moving the incubator to a new area, place a water level on the second shelf of the incubator and check that the incubator is leveled. As the manufacturer directs, level the incubator by adjusting the feet or the base of the stacking stand. 

Strengths and Limitations 

The CO2 incubator maintains an adequate environment for cell growth. Although standard incubators maintain the humidity and temperature inside the chamber, the CO2 incubator also maintains the pH. This makes it more suitable for various applications involving cell or tissue culture, including in-vitro fertilization and tissue engineering. Another advantage of the CO2 incubator is its LCD screen that saves data in real-time. It is also equipped with a built-in sensor that maintains the desired CO2 concentration. 

It is important to prevent leaving the incubator door open for too long as this can lead to contamination of the samples. A limitation of using the incubator is that it can only incubate cultures at a specific temperature, humidity, pH, and CO2 concentration. Therefore, multiple cultures requiring different environmental variables need to be incubated separately, which can take a lot of time if only one incubator is available. 

Summary 

• The CO2 incubator provides an optimal environment for cell and tissue culture growth. 
• It maintains a constant temperature, humidity, and pH with CO2 control. 

• The CO2 incubator can be used in tissue engineering, in vitro fertilization, medical research, diagnostics, and developing biosensors. 
• The incubator includes an LCD screen that saves data in real-time. It also maintains CO2 concentration since it has a high-quality infrared sensor. The incubator includes two shelves with holes that evenly distribute the temperature the humidity throughout the chamber. 

References 

1. Tripathi, G., & Basu, B. (2012). A porous hydroxyapatite scaffold for bone tissue engineering: Physico-mechanical and biological evaluations. Ceramics International, 38(1), 341-349
2. Iwayama, H., Ishikawa, H., Ohsumi, S., & Fukui, Y. (2005). Attempt at in vitro maturation of minke whale (Balaenoptera Bonaerensis) oocytes using a portable CO2 incubator. The Journal of reproduction and development, 51(1), 69–75. https://doi.org/10.1262/jrd.51.69
3. Nabavi, N., Todehdehghan, F., & Shiravi, A. (2013). Effect of caffeine on motility and vitality of sperm and in vitro fertilization of outbreed mouse in T6 and M16 media. Iranian journal of reproductive medicine, 11(9), 741–746.
4. Domansky, K., Inman, W., Serdy, J., Dash, A., Lim, M. H., & Griffith, L. G. (2010). Perfused multiwell plate for 3D liver tissue engineering. Lab on a chip, 10(1), 51–58. https://doi.org/10.1039/b913221j
5. Zimmerman, J. J., Jacobs, A. C., Hermann, J. R., Muñoz-Zanzi, C., Prickett, J. R., Roof, M. B., & Yoon, K. J. (2010). Stability of Porcine reproductive and respiratory syndrome virus at ambient temperatures. Journal of veterinary diagnostic investigation : official publication of the American Association of Veterinary Laboratory Diagnosticians, Inc, 22(2), 257–260. https://doi.org/10.1177/104063871002200216