An Introduction to Cryogenics

Cryogenics involves the production and study of materials in extremely cold temperatures. Ultra-cold temperatures are able to augment a material’s chemical properties. This has become a key area of study for researchers investigating various materials as they are transformed from a gas to a liquid to a solid state.

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Cryogenic studies have led to significant scientific breakthroughs, not only in terms of understanding different materials, but they have also brought about the creation of entirely new technologies and industries.

The energy contained in any material is often measured by its temperature; rapidly moving molecules possess a higher temperature than slower-moving molecules.

For instance, while water goes from a liquid to a solid, freezing at 32 °F (0 °C), cryogenic temperatures hit much lower ranges, from -150 °C to -273 °C. The temperature -273 °C is the lowest that can be feasibly achieved.

At this temperature, all molecules are stripped of any active qualities as the molecules are at the lowest possible state of energy.

Liquid gases at or below -150 °C are used to freeze other materials. Once a gas transforms into a liquid state, the environment is classified as a cryogenic one. The most frequently used gases in cryogenic applications are oxygen, nitrogen, hydrogen, and helium.

History of Cryogenics

The word cryogenics derives from the Greek word “Kryos,” which means cold. Combined with the abbreviated form of the English word “to generate,” the neologism we now know as cryogenics is formed.

Extremely cold temperatures are not measured in degrees Fahrenheit or Celsius but in Kelvins, denoted by the unit symbol K. Named after Baron Kelvin, who believed that a new scale that was not measured by the material state change of water like Fahrenheit or Celsius was necessary to represent extremely low temperatures. In theory, zero degrees Kelvin (0 K) is the coldest possible temperature that can be achieved.

In 1877, oxygen was liquefied for the first time by Rasul Pictet and Louis Cailletet, both using different process methods for the same result. In time, a third method of liquefying oxygen emerged, and it was this development that enabled the liquefaction of oxygen at 90 K. Shortly after, liquid nitrogen was produced at 77 K. Scientists across the globe began competing to try to get the temperature of matter to absolute zero.

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The next innovation came in 1898 when James DeWar liquefied hydrogen at 20 K. This presented researchers with a new problem, as 20 K is also very close to the boiling point of hydrogen.

Consequently, this presented issues related to the handling and storage of gases at such temperatures. This led to the creation of DeWar flasks, which are still used for the storage of gases today.

The last major breakthrough in the cryogenics industry came in 1908 when the physicist Heike Kamerling Onnes liquefied Helium at 4.2 K and then again at 3.2 K. The progress since then in cryogenics has been relatively slow because thermodynamic law dictates that you can come close to absolute zero but never actually reach it.

Technology has progressed so much more since the last major cryogenics discovery, and materials can now be frozen within striking distance of absolute zero, yet scientists are still obstructed by the thermodynamic law that states every particle has zero energy.

What is Cryogenics Used For?

Cryogenics finds utility across a wide range of low-temperature physics research and development applications. It can be used to manufacture cryogenic fields for rockets, the helium-based liquids used in MRI machines that require cryogenic cooling, storing vast amounts of food, recycling, freezing blood, and tissue samples, special effects fog, and even cooling superconductors.

Applications and Uses:

Cryosurgery

Cryosurgery is a type of surgical technique that involves the use of extreme cold to destroy or remove abnormal tissues, such as tumors or warts, with minimal invasion. The procedure typically involves the direct application of a freezing agent, such as liquid nitrogen or argon gas, onto the targeted area. As a result, the tissue freezes and ultimately dies, allowing the body to eradicate the damaged cells naturally.

The science that drives cryosurgery is predicated on the principle of controlled tissue destruction by rapid freezing and thawing. When the tissue being targeted is exposed to sudden extreme cold, the water inside the cells freezes and expands. This causes ruptures in the cell walls, and the cells simply die. The body’s immune system then kicks in and removes the dead tissue, replacing it with healthy tissue in the process.

Cryosurgery has a number of benefits compared to conventional surgical techniques. It is minimally invasive and can typically be performed on an outpatient basis, a procedure that reduces the necessity for hospitalization and recovery time. It also produces less scarring and pain in contrast to conventional surgical techniques and has a reduced risk of infection and complications.

Cryosurgery is frequently used in dermatology to treat skin conditions such as actinic keratosis, warts, and skin cancers. It also finds use in other medical specialties, such as gynecology, urology, and gastroenterology, to treat a variety of conditions.

Cryoelectronic Cooling

Cryoelectronic cooling is a groundbreaking technology that has radically changed the fields of superconductivity and spacecraft design. By leveraging extremely cold temperatures, this process allows the electrons in materials to move freely with minimal resistance.

This technology has numerous advantages over conventional cooling methods, such as liquid cooling, because it is more reliable, efficient, and cost-effective.

In superconductivity research, cryogenic engineering is pivotal when it comes to maintaining the low temperatures that superconducting materials need to operate at to achieve their full potential.

These materials have the capacity to conduct electricity with zero resistance when they are cryogenically cooled close to absolute zero (-273.15 °C).

By leveraging cryoelectronic cooling, scientists can reach and maintain these extremely low temperatures, facilitating the creation of more efficient and powerful superconductors.

Besides superconductivity research, cryoelectronic cooling has applications in spacecraft design.

Spacecraft that are sent into outer space are prone to experiencing extreme temperatures, which can damage vital electronic systems. Cryoelectronic cooling offers a reliable and efficient way to ensure the temperature of electronic systems in spacecraft remains intact, allowing them to operate at optimal performance levels.

One of the key benefits that cryoelectronic cooling offers is that it is an extremely efficient method of cooling. It requires only a small amount of energy to sustain extremely low temperatures. This makes it the perfect choice for space-based applications, where conserving energy is crucial.

Furthermore, cryoelectronic cooling is a cost-effective, reliable method of cooling, with only a few moving parts; it minimizes maintenance requirements.

Cryobiology

Cryobiology involves the study of how low temperatures impact living organisms. There are six key areas of cryobiology:

• Cryosurgery
• Cryopreservation of cell tissues and embryos used in invitro fertilization
• Organ preservation
• Lyophilization, the freeze-drying of pharmaceuticals
• Supercooling as applied to biological systems
• The cold-adaptation study of animals plants, microorganisms, and vertebrates

Food Preservation

Cryogenics facilitates the storage of fresh food without any chemical risk. It is a useful technique for preserving food while maintaining the quality and freshness of various products. 

Cryogenic preservation is not just about making something cold; it freezes food products so rapidly that consistency, texture, and taste are all preserved. This makes cryogenic preservation an ideal choice if storing high-value food items such as seafood, meat, and vegetables.

This method is extremely useful if an application requires preservation of the texture and quality of delicate food products that other preservation methods, such as dehydration or heat treatment, would compromise.

Another advantage of cryogenic preservation is its capability to increase the shelf life of food products. By using ultra-low temperatures to freeze food products, the growth of microorganisms that typically lead to spoilage and decay is impeded. As a result, this reduces the risk of foodborne illness and improves overall food safety.

To preserve packaged foods such as produce, liquid nitrogen is usually sprayed onto the food items to absorb any heat within the produce. The nitrogen rapidly evaporates before the food is packaged. 

Transportation of Gases

Cryogenics finds useful applications in the transportation of gases that are not typically cryogenic. For instance, using cryotechnology, it is possible to transform gases into liquids. This makes it easier to transport them from one place to another.

When the gasses found in natural gas (LNG), which combines ethane and methane, become liquefied, they occupy far less space than if they stay in their gaseous states. Resultingly, the costs of transportation are reduced and the overall process becomes much easier.

Cryotherapy

Cryotherapy is a medical treatment in which the human body is exposed to extremely cold temperatures. Various methods are used to achieve the desired results. These include cryosaunas and cryospas, in which individuals stand in a chamber filled with cryogenic fluids for several minutes at a time.

Advocates of cryotherapy claim that it provides a number of benefits to the body, such as reducing inflammation, managing pain, increasing energy, and boosting metabolism. While research on cryotherapy is still in its early days, multiple studies have revealed that it can be effective when it comes to reducing inflammation and pain in certain chronic conditions, such as rheumatoid arthritis and fibromyalgia.

However, cryotherapy presents a series of potential risks. Excessive exposure to cold temperatures can lead to a heightened risk of hypothermia, which, in the worst-case scenario, can be life-threatening. Additionally, cryotherapy leads to skin damage, especially if the skin is wet or has open wounds.

Furthermore, while cryotherapy may offer some individuals immediate relief from pain and inflammation, the long-term benefits of the treatment are not entirely unclear. Other studies indicate that cryotherapy may not be as effective for all individuals and may even be dangerous in some cases.

Cryonics

Cryonics, or cryo-preservation, is the process of freezing animals or humans in the hope of reviving them at a later point in time when medical technology is sophisticated enough to cure the underlying cause of their death. Cryonics involves cooling the body to extremely low temperatures using a cryonic container filled with liquid nitrogen.

The cryopreservation process is typically performed immediately after the moment of death or sometimes before if the individual is terminally ill and has elected to undergo cryonic preservation.

Cryonics aims to preserve the brain and other vital organs to facilitate a full revival of the frozen person with their memories, consciousness, and personality intact at some point in the future.

While cryonics is deemed a controversial topic, advocates for the technology argue that it offers hope for individuals who have received a diagnosis of terminal illnesses or those who may die from other unexpected causes.

They argue that in the future, progress in medical technology may be so advanced that it will be possible for future medical professionals to revive and cure the underlying cause of death. This would allow individuals to continue living later on.

Critics, however, claim that cryonics is a pseudoscience and that reviving an individual successfully will not be possible. They also argue that the body is subjected to major damage during the process of cryopreservation and that it is unethical to offer individuals and their families false hope.

What are the Cryogenic Fluids? 

What is Next for Cryogenics?

As the technology rapidly evolves across all areas, so will the development of cryogenics, which will expand to even more applications. While it is not possible to predict what the next major breakthrough will be, safety around cryogenic fluids remains crucial regardless of how the research advances.

All applications that necessitate the handling, study, and use of cryogenic liquids must practice appropriate safety precautions. Furthermore, cryogenic oxygen depletion monitors should be used to monitor gas concentrations safely and accurately.

References

1. https://academickids.com/encyclopedia/index.php/Cryogenics
2. https://schoolworkhelper.net/cryogenics-history-overview/
3. https://www.encyclopedia.com/science-and-technology/physics/physics/cryogenics
4. https://www.azonano.com/article.aspx?ArticleID=5091
5. https://science.jrank.org/pages/1893/Cryogenics.html
6. https://www.thoughtco.com/cryogenics-definition-4142815
7. https://www.healthline.com/health/cryotherapy-benefits#benefits
8. https://www.chilledcryospa.com/what-is-cryo
9. https://en.wikipedia.org/wiki/Cryosurgery
10. https://en.wikipedia.org/wiki/Cryoelectronics
11. https://en.wikipedia.org/wiki/Cryobiology
12. National Institute of Standards and Technology, Public domain, via Wikimedia Commons

This information has been sourced, reviewed and adapted from materials provided by CO2Meter, Inc.

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