The desire to have children is a fundamental hope for most couples in fulfilling their life’s plans but this can be very stressful for couples affected by fertility. IVF is an assisted reproductive technology procedure where fertilization occurs “outside of the body in an incubator under controlled conditions”.

In Vitro Fertilization is used when female is the primary cause of the infertility (Endometriosis, Tubal disease, Hormonal dysregulation and Polycystic ovary syndrome) and Intracytoplasmic Sperm Injection (ICSI) is used in case of male infertility (if the quality of man sperms is inadequate).

“Incubators are vital to the overall success of IVF. They create the optimal, constant environment for embryo cultures. Good embryo culture conditions and subsequent embryonic development are dependent upon a correctly maintained incubator temperature and pH.

The most commonly used environmental conditions for human IVF incubators are 5% CO₂ in air, 37°C, and 100% relative humidity. CO₂ Incubators are the most important equipment for the IVF because the eggs harvested from the ovaries of the patients for fertilization spend most of the time outside the body that is in the incubator. Because this unit gives the special environment conditions of the body like 37°C (body temperature) and 5-7 % CO₂ maintain the physiological pH value of the cultural medium used and offer the best conditions for optimal oocyte and embryo development.

CO₂ is used to regulate the pH level, thus pH is measured and maintained by monitoring and adjusting the concentration of CO₂. CO₂ and pH have an inverse relationship; as the concentration of CO₂ increases, pH level decreases.

How does IVF works?

In vitro fertilisation is a three stage procedure involving

• Collecting eggs and sperms; an initial phase of injections to stimulate the growth of multiple eggs (typically 12 to 14 eggs are obtained in each cycle). The eggs are then collected through the vagina using ultrasound. This procedure is best performed under a light anaesthetic. The male partner usually would produce sperm on the same day although depending on the individual circumstances sperm can be kept frozen at the sperm bank or clinic. In IVF each egg is then placed in a droplet of culture fluid containing all the nutrients required for embryo development and approximately 50,000 sperm are added to each egg.
• Incubation; The sperm and eggs are then cultured overnight in an incubator mainly CO₂ Incubator.
• Collection of fertilized eggs; eggs are examine for the sign of fertilization. The fertilised eggs are allowed to develop for a further 48 hours until they reach the day 3 stage when one anticipate that the best embryos will have between 6 and 8 cells..

Embryo transfer is a very important process in which the best embryos are placed in mother’s uterus. Pregnancy rates during IVF treatment is dependent on a number of factors such as the women’s age, hormone levels, associated gynecological conditions such as endometriosis, fibroids, ovarian cysts and pre-existing medical conditions.

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As it is very well known that incubator maintains optimal temperature, humidity and other conditions such as Carbon dioxide (CO₂) and oxygen content of the atmosphere inside. CO₂ incubator controls the CO₂ level to 5% and it works on three building blocks

• Carbon dioxide
• Temperature
• Relative Humidity

CO₂ incubators are usually set to 37°C. This is the optimal working temperature for promoting healthy cell growth. The external indicators of the incubator do often provide a good sense of the internal environment, but it is often useful to keep a good thermometer inside to keep a record of the internal temperature.

The chambers of CO₂ incubators are sometimes incorporated with copper which is used for eliminating the contamination in incubators, as copper breaks down it releases copper oxide which destroy microbes that are present in the chamber.

CO₂ incubator may be

• Water-jacketed; envelopes the unit’s chamber and provides superior insulation while eliminating contamination and cold spots.The water-jacket is also surrounded by insulation, which makes the incubator ideal for maintaining precise conditions.

• Air-jacketed; an air-jacket CO₂ incubator has a heated inner chamber that is controlled by sophisticated microprocessors. These microprocessors constantly monitor and adjust program settings and allow calibrations of CO₂ and temperature.

For both types of incubators, the microcomputer controls include backup systems that prevent samples from overheating, plus alarms that monitor the out-of-tolerance conditions.

Maintaining the chamber’s environment (CO₂ control)

To maintain the chamber environment for safe and reliable research, CO₂ incubators are equipped with precise automated controls. These controllers are of three types.

• Continuous Flow; provides manual control of the air and CO₂ flow rate through the use of precision-bore glass tube flow meters. For this method an accessory air pump is required.
• Thermal Conductivity (TC)sensor ; more indirect method of CO₂ detection and control since it measures the level of CO₂ by sensing temperature differences as CO₂ is introduced into the chamber.
• Infrared (IR); This method uses an infrared sensor to detect a change in CO₂ concentrations as little as 0.1 %. Since the IR sensor is unaffected by changes in temperature and humidity, it is ideal for applications in which the incubator door is frequently opened, and provides nearly perfect culturing conditions for cell growth. The sensor continuously samples chamber atmosphere through a spectrophotometer flow cell, checking wavelength and instantly correcting an out-of-control condition. Also, CO₂ recovery is rapid and changes in CO₂ concentration are made within seconds.

Areas of Application

• Tissue Culture
• Food and dairy processing
• Stem cell research
• Biochemical, bacteriological and hematological studies
• In vitro fertilization
• Virological studies

Safety Guidelines

• Incubator should be located on a solid work surface that should be away from high traffic areas and extreme temperatures (Constant temperature is easier to maintain if the incubator is not in the direct contact of airflow from air conditioners or heat sources.
• Electrical cord of the incubator should be routinely inspected for any damage (Electrical cord should not be used for cord repair).

• This thermometer must also be cleaned with 70% alcohol on a regular basis to maintain its integrity.
• The internal humidity of the incubator is usually maintained, by a tray of water which is kept topped up on a weekly basis. It is essential to always use sterile distilled water to do this.  The tray which holds the water must also be cleaned to prevent the expensive and time-consuming results of contamination by unwanted invaders. The incubator should be cleaned with 70% alcohol between uses and internal removable parts should be autoclaved to achieve full sterilisation.

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