What is Ultrasonic Cavitation?

What is ultrasonic cavitation liposuction? Let’s talk theory. Ultrasonic cavitation is the phenomenon that results from high intensity, high frequency ultrasound waves being directed into a liquid. The bombardment of a liquid by these waves results in tiny cavities being formed in the liquid at a microscopic levels.

The sound waves penetrating the liquid case an alternating pressure cycle to occur in the liquid. The pressure cycle is dipolar, with one part of the cycle being a high-pressure cycle (referred to as a compression cycle, where the liquid is being compressed at a microscopic, local level), and the second part being a rarefaction cycle, where the pressure is lower and the liquid re-expands after being compressed. Although the effect isn’t seen on a macro level and can only be observed through a microscope, the effects of cavitation can be very extreme at the local level. It can cause liquid jets of up to 300m/s or 1000km/hr to occur. And just to further elaborate on the power of UC, another local, microscopic effect is the formation of pressures of up to 2000 atmospheres and temperatures of up to 5000K. Now, these extremes only exist at the microscopica level, and only last for a fraction of a second. However, their power is in that they occur throughout the liquid, and that they occur over and over again, many millions of times per minute.

Here is a Great Video With a Little More Information on UC:

Cavitation Cycles

The number of times that the aforementioned cycles occur per second is related to the frequency of the ultrasonic vibrations. When the rarefaction cycle occurs, the ultrasonic waves cause tiny bubbles to form in the liquid in question. These bubbles do not contain air, but can rather be thought of as “voids”, where a vacuum exists for a split-second. On the other hand, the compression cycle occurs after the rarefaction cycle completes. When the rarefaction cycle is at it’s peak, the “void-bubbles” have expanded to a level at which they are maxed-out for energy. They are at an energy saturation point, and cannot absorb any more. They then collapse, almost like a nova forming a black hole. The entire phenomenon, constisting of both parts of the cycle, is what is referred to as cavitation. Cavitation can result from different processes than just ultrasound waves. However, when ultrasonic waves are the cause, then the process is referred to as ultrasonic cavitation.

I go much further into the applications of UC in another article. However, just to touch on a few applications in this primer, some of the uses for UC are industrial: milling, cleaning, mixing, blending, deagglomeration are just a few. And then the study of ways to prevent UC is another industrial application, as cavitation which occurs at high speeds when a propeller is running can quickly lessen the lifespan of the parts. The other side of cavitation is ultrasound cavitation in a biomedical setting. Ultrasonic cavitation is beginning to replace certain types of cosmetic surgery, notably liposuction. It’s not appropriate in all circumstances and for all people, but cavitation is on the rise as a lipo alternative in many urban centers around the world. The benefits are that the surgery is non-invasive and painless. It uses the dipolar cavitation cycle to collapse fat cells, essentially using ultrasonic waves or cell disintegration. The fat is then excreted in the urine in the days following the procedure.

That’s my introduction to ultrasonic cavitation. Make sense? Let me know if you have questions.