Sonication: What Is It?

Sonication is the process of using energy to move particles around in a solution, typically for the purpose of cleaning or separating different substances. Sonication sends ultrasonic frequencies into a solution or sample, for example when cleaning jewelry and removes dirt and debris.

Beyond speaking and communicating our internal thoughts, sound can become a tool to shape and understand the world around us through processes like sonication.

Sound is a crucial part of our senses because we use it to hear things. These things can be the sound of other people, animals, and even danger among many other sound sources. When a police car or firetruck is nearby, we hear the sirens that they make to alert us to their presence.

While there are many people unable to hear a sound, they can also feel it because the sound is the vibration of particles. Sonication harnesses the power of sound for a variety of purposes.

Sonication is using sound energy (in the form of the vibrations) to agitate a sample with the purpose of breaking it apart. The frequencies that it operates on are beyond human hearing and create so much vibrational energy that they are used across many industries.

Sonication devices can be found in the food industry, pharmaceutical industry, nanotechnology, water industry, and many others because they depend on its ability to break things apart into much smaller pieces.

The diversity of industries that uses sonication for similar purposes highlights the versatility of sound as a tool of science and research.

Uses of Sonication

Ultrasonic Cleaning

Ultrasonic cleaning is a form of sonication that got its commercialized start in the 1950s as more industries started using it for cleaning purposes. It uses high-frequency sound waves in a liquid medium to induce cavitation. Cavitation is the formation of tiny bubbles, created by the sound waves, that collapse and create a shock wave.

For the purposes of cleaning things like jewelry, the ultrasonic cleaning devices cause many mini shockwaves in the liquid solution, which agitates the dirt on the jewelry. This agitation breaks apart the dirt and causes them to fall away from the jewelry, making it cleaner.

This method of cleaning is very helpful when trying to clean things that have lots of intricate and small parts, which would be inaccessible through normal means of cleaning.

Ultrasonic cleaning is used to clean metals, glass, plastics, and many other mediums. It is used to remove dirt, fungus, blood, grease, and many other unneeded compounds.

Devices Cleaning Device Ultrasonic Cleaner. Credit: Maxpixel

Cell Lysis

Cell lysis is the breakdown of a cell structure to release the internal contents, which includes proteins and DNA among others. It is a common laboratory method employed to extract particular components of a cell.

There are a few different methods for this. Cells can be frozen and thawed, which is a very slow process. There are chemical and enzymatic methods, which can create additional problems of purification and reproduction. There is also sonication.

Sonication is employed here to agitate the cells via a process called sonoporation. Like ultrasonic cleaning, sonoporation devices uses the high-frequency sound waves to create disruptions to the cell and cause the cell wall and/or membrane to slowly or quickly fall apart.

Once the protective outer layer of the cell is broken, its internal contents are released. At this point, the cell is lysed and researchers can apply additional methods to extract the pieces they want.

Conversely, sonication can also be used to simply increase the permeability of the cells. This would allow them to accept foreign compounds, like viral RNA, into the cell. Researchers use this method to study the effects of viral RNA to the cells function.

Food Industry

Sonication in the food industry is used for a variety of purposes that includes cleaning as well. One of the uses of sonication is emulsification.

Emulsification is the process of mixing two substances that normally do not mix well. Since the process of sonication breaks down things into very small pieces, emulsification via sonication creates a more evenly mixed product versus using chemicals, which can be more expensive.

Sonication has also been used to filter oils as it helped to break down the byproducts and make them easily removable.  Another use of it is the extraction of things like antioxidants from fruits and vegetables. Antioxidants have been found to potentially have positive effects on the human body, so demand for them has increased.

In 2013, researchers found that sonication was an effective method of extracting bioactive compounds from red raspberries. The sonication broke down the fruit enough that they were able to get a lot of antioxidants. They also noted that sonication had limits on this because too high frequencies resulted in fewer compounds being extracted. If the sonication went on for too long, it did not add anything positive to the extraction.

Researchers from the WSU and UI found that sonication could be used to effectively extract antioxidants from fruits, like red raspberries.

Buzz Pollination

Sonication is not a human only activity because it has been observed in bees. Buzz pollination is a form of sonication that is employed by bees. It is used to release pollen held by the anthers of plants, the pollen reproductive organ of flowers. This tactic is mostly held by solitary bees, like carpenter bees, rather than those like honey bees.

Buzz pollination works when solitary bees latch on to a particular flower and move their flight muscles quickly to vibrate the flower’s anthers at a specific frequency. This vibration causes the pollen to become dislodged from the anther and onto the bee.

About 8% of flowering plants are known to employ buzz pollination to let bees have their pollen. The reason that bees go through all the trouble is that they want the pollen to eat. These plants offer pollen instead of nectar as a food source.

Once the bees have the pollen on them, they go to other flowers and try to get food. This causes a transfer of the pollen onto the new plant, which aids in successful plant reproduction.

This creates a mutually beneficial relationship that has allowed these few plant species to thrive and continue to grow.