Incubator Working Principle

A sealed, insulated apparatus called an incubator is employed in biological laboratories. By offering the ideal temperature, humidity, and other environmental factors, like the CO2 and oxygen content inside, it generates the perfect environment needed for the growth of microorganisms. It is used in laboratories to develop and preserve cell or microbiological cultures. An incubator is used to develop organisms with bacterial and eukaryotic cells. Additionally, an incubator is utilized to maintain an atmosphere suitable for a newborn baby and utilized for some sick full-term newborns or premature births. The incubator is the ultimate equipment for growing and storing bacterial cultures. The temperature range may range from 0 degrees Celsius to 80 degrees Celsius (according to the model).

What is an Incubator Machine?

In short, an incubator is a machine used for the incubation process that raises the temperature of an enclosed to a predetermined level and maintains all artificially ideal circumstances for the growth of the microbial culture. Therefore, incubation is a period during which environmental factors such as humidity, temperature, and others offer the ideal temperature for the establishment and growth of the microbial culture.

Brief History of Incubator

Incubators’ history started in ancient times, but their primary function is to establish a stable, regulated environment suitable for research, study, and cultivation has remained constant.

In the early years, Ancient Egypt and China were where the first incubators were created, and they used to keep chicken eggs warm. Early incubators in Egypt and China were huge rooms heated by fires, where attendants periodically rotated the eggs to guarantee even heating. In the 16th century, Jean Baptiste Porta updated the egg incubator by drawing inspiration from ancient Egyptian architecture.
In the 17th century, Reaumur used a wood burner to warm his incubator and created the Reaumur thermometer to keep track of its temperature.

Researchers finally realized in the 19th century that using incubators could enhance medicine. They started testing to determine the best conditions for preserving cell culture stocks. These early incubators were just simple bell jars with lit candles. On the underside of the jar’s lid, cultures were placed close to the flame, and the entire jar was then placed in a dry, hot oven. The CO2 incubator, which was released to the market in the 1960s, was the next advancement in incubator technology.

At this time, genetic engineering also started to use incubators. Scientists could use incubators to produce biologically necessary proteins, such as insulin. In order to increase the nutritional value and disease resistance of fruits and vegetables, molecular genetic manipulation is now possible with advancements in technology. Hence incubators of a variety of sizes and different types are available.

Incubator Working Principle

The thermo-electricity theory, which states that heat or thermal energy can be converted into electrical energy, is the foundational idea behind an incubator. Every incubator operates under the fundamental element that microorganisms need the ideal environment to live and grow. The perfect temperature, humidity, oxygen, and carbon dioxide are all present in an incubator, allowing the microorganisms to grow and increase in population. An incubator’s thermostat controls the temperature within the incubator. We can use the thermometer to check this temperature outside.

We keep the temperature within the incubator constant by heating and no heating cycles. In the heating cycle, the incubator’s temperature is raised by the thermostat, but in the non-heating process, the incubator is cooled by radiating heat outward. The cabinet has a system of insulation that keeps it isolated from the outside and promotes efficient microbial growth. Similarly, the incubator also maintains other conditions necessary for the development of the organisms, such as humidity, ventilation, CO2 concentration, and pH, using various processes. A shaking incubator variation of the incubator enables the constant shaking of the culture needed for investigations on cell aeration and solubility.

Procedure for Running an Incubator

The culture plates must be placed inside an incubator at the required temperature for a specified time once the organism cultures have been established. The typical temperature to be maintained in most clinical laboratories for microorganisms is 35–37°C.
The procedures that must be followed when operating an incubator are as follows:

• The incubator should be checked to make sure that there are no leftovers from previous cycles before use. However, there are some situations when numerous species can be placed in the same incubator if they all require the same environmental conditions.
• Next, the incubator’s door is kept closed, and it is turned on. The incubator’s temperature must be raised to that required for an organism’s growth. To determine whether the temperature has reached, use the thermometer.
• Meanwhile, the incubator’s specifications should also be set if the organism needs a specific CO2 concentration or level of humidity.
• After all the criteria have been satisfied, the cultures in Petri dishes are placed on the perforated shelves upside down, with the media at the top.
• If the plates are incubated regularly, condensation would build up on the medium’s surface and limit the growth of isolated colonies.
  If Petri dish cultures need to be incubated for several days, the plates are either sealed with adhesive tapes or put in plastic bags or food containers. The door is now locked, and the plates are maintained there for the necessary time before removal.

Components of Incubator

Different components of an incubator work together to maintain the ideal environment needed for bacterial development. The following are the parts of the incubator:

1. Cabinet: The cabinet comprises a double-walled cuboidal box with a volume ranging from 20 to 800L, the incubator’s main structural component. Aluminum is used for the inside wall, and stainless-steel sheets are used for the outside. Glass wool is used in the gap between the two walls to insulate the incubator. The insulation guarantees the device’s smooth operation by preventing heat loss and lowering electric consumption. The incubator’s interior wall has inward extensions that support the shelves inside the incubator.
2. Door: The door is located at the incubator’s front. Each incubator has a door that can be closed to seal the insulated cabinet. Additionally, the door has insulation. Additionally, a window is included, allowing for visualization of the incubator’s inside during incubation without disrupting the environment. The door has a handle on the outside to facilitate opening and closing.
3. Control panel: A control panel with all the switches and indicators that enable the parameters of the incubator to be controlled is located on the incubator’s an outside wall. The device’s thermostat is also controlled by a witch on the control panel.
4. Thermostat: The incubator’s desired temperature can be set using a thermostat. When the incubator reaches the desired temperature, the thermostat automatically holds it there until the temperature is adjusted once more.
5. Perforated shelves: A few perforated shelves are attached to the interior wall and are used to hold the plates containing the culture media. The shelves’ perforations enable hot air to circulate throughout the incubator’s interior. Some incubators have removable shelves, allowing for thorough cleaning of the shelves.
6. Asbestos door gasket: A nearly airtight seal is provided between the door and the cabinet by the asbestos door gasket. This seal keeps outside air from entering the cabinet, isolating the cabinet’s hot climate and preventing interruptions from the outside world.
7. Thermometer: The thermometer is in the upper portion of the cabinet’s exterior wall. The thermometer contains a mercury bulb embedded into the incubator on one end and gradations on the other that show the temperature.
8. HEPA filters: HEPA filters, which are also included in some incubators, help to lessen contamination caused by airflow. It is connected to an air pump that circulates the air inside the incubator to limit the likelihood of contamination.
9. Humidity and gas control: Water is contained in a reservoir beneath the chamber of the CO2 incubators. The water is vaporized to keep the relative humidity within the chamber. Similar to other incubators, these have gas chambers that allow for the desired CO2 concentration inside the incubator.

Types of Incubators

There are numerous varieties of incubators. These are categorized based on the kinds of criteria or the incubator’s intended use.

1. Benchtop Incubators: These are the most popular incubators found in laboratories. These incubators are the fundamental kinds, provided with insulation and temperature control.
2. CO2 Incubators: CO2 incubators are specialized incubators with CO2 and humidity levels that are automatically controlled. This incubator is used to grow various bacteria that need a CO2 concentration of between 5 % and 10%. Water is kept below the incubator’s cabinet to regulate humidity.
3. Cooled Incubators: This type of incubator has been allowed to cool. They have a refrigeration system with both cooling and heating capabilities. It is utilized at temperatures lower than the ambient to incubate the culture media. This incubator’s heating and cooling controls need to be correctly adjusted.
4. Shaker Incubator: This incubator has a shaker that continuously agitates the culture material to ensure proper aeration. Within the incubator, it distributes the heat uniformly.
5. BOD Incubator (Biological Oxygen Demand): As yeast and molds (fungus) require low temperatures to grow, these incubators are frequently referred to as low-temperature incubators. This incubator is called a BOD (biological oxygen demand) incubator because a low temperature of 20 to 25 °C is required for measuring biological oxygen demand. The cooling and feeding systems in the BOD incubator set it apart from the bacteriological incubator. BOD incubators are entirely independent and unaffected by their surroundings.
6. Portable Incubator: Smaller portable incubators are used for fieldwork like environmental microbiology and water testing.

Application(s)/ Use(s) of Incubators

1. Using incubators for cell culture growth.
2. Germ cell reproduction and subsequent count in the food industry.
3. Cell growth and following assessment of the biochemical oxygen demand (wastewater monitoring).
4. Reproduction of microscopic creatures like viruses, fungi, or bacteria.
5. Insect reproduction and egg development in zoology.
6. Regulated sample storage.
7. Crystal/protein crystal growth.

Disadvantage(s)/Limitation(s) of Incubators

1. The cost of purchasing an incubator is high. Most incubators are very expensive and out of the reach of small-scale farmers.
2. It needs a lot of work because there will be a lot of turning of eggs.
3. Running and maintaining an incubator takes a lot of expertise.
4. To function, the incubator needs a power supply. Finding a stable power supply is a huge problem in most rural and isolated places.
5. Finally, it can induce egg cracking, especially during egg turning, and has a significant risk of harming the embryo.

Precautions/Safety Measures

1. Ensure enough water is underneath the shelves before running an incubator; otherwise, the culture media will start to dry out.
2. Regularly clean the incubator to prevent the accumulation of organisms on its shelves or corners.
3. Place the plates upside down with the lid at the bottom to prevent condensation of water onto the media.
4. Verify that the required parameters are met before putting the culture plates into the incubator.
5. Avoid repeatedly opening the incubator’s door when it is operating.

This article describes what an incubator is, how it works, its working principle, and a brief history of the device. An insulated and sealed biological laboratory tool is what is generally referred to as an incubator. An incubator device is used in the incubation process to preserve all artificially optimum conditions for the growth of the microbial culture while raising the temperature of an enclosed space to a  predetermined level. We also discuss the many kinds of incubators, their components, and their benefits and drawbacks. We conclude by discussing the safety considerations that should be taken when using an incubator.