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Home > Nanotechnology Columns > Magda Carvalho PhD, JD > Patenting Cavitation Technology

Magda Carvalho
Patent Attorney
Patent Law at M. Carvalho

Cavitation technology—behavior of voids or bubbles in a liquid—offers tremendous promise for humanity. It is a growing technology as seen by the race to patent anything related to cavitation since weapons, treatment of wrinkles to a cleaner environment.

April 7th, 2009

Patenting Cavitation Technology

This column reports some fields where cavitation is seen at work. The patents described here are used only to exemplify the wide range of the fields where this technology has been applied. More information about current developments related to cavitation provided by experts is now available at LinkedIn:Group— Advanced Cavitation Institute for Alternative Energy, formed by Sergio Lebid.(1)

Cavitation is a general term used to describe the behavior of voids or bubbles in a liquid. Major places where cavitation occurs are in pumps, on propellers, or at restrictions in a flowing liquid. Cavitation is usually divided into two classes of behavior: inertial (or transient) cavitation and non-inertial cavitation. Inertial cavitation is the process where a void or bubble in a liquid rapidly collapses, producing a shock wave (which may be audible). Such cavitation often occurs in pumps and impellers (small bubbles of gas). Non-inertial cavitation is the process where a bubble in a fluid is forced to oscillate in size or shape due to some form of energy input, such as an acoustic field. Such cavitation is mostly employed in ultrasonic cleaning baths, but can also be observed in pumps and propellers.(2,3)

Patents offer pathways for generating, disseminating and implementing valuable new technologies for greater public welfare. The function of the patent system is to deliver information to the public. The patent system discloses not only legal information but also technological information. As such, it can be seen that there are lots of potential commercial applications for nano-based cavitation technologies. Markets that show a patent profile include since crude oil enhancement, water sanitation, weapons to pharmaceuticals as exemplified by the following issued patents.

Treatment of Food.
The US Patent 3743523 provides an example where production of cavitation is either wanted or not. The patent is for a method for the sonic treating of food material. Cooking of food requires water to penetrate the solid particles. Penetration is required whether the food is cooked with a heating process or simply prepared by soaking. High level sonic energy is utilized to generate elastic pressure pulses in a liquid in which food material is immersed. By transmitting sonic energy the solids are efficiently worked with the liquid. The result is a faster process of hydration and cooking. Cavitation is at work in the separation of meat from bone and detachment of starches and proteins from basic food stock and to cause homogenization of food products. High cavitation causes sterilization and also stops enzymatic action. However, cavitation is not desired if moisture is to be added to the food, as such the level of sonic energy below that required to produce cavitation in the liquid.

Extraction of Coffee and Teas.
The US patent 3902273 provides a method for subjecting the vegetable to the effect of cavitation produced by ultrasonic sound waves. The patent describes several results possible by cavitation including inhibition of germination of seeds and sprouting, rupture of the cytoplasmic membrane of algae and extraction of coffee and tea. Regarding coffee and tea, the patent describes that cavitation adopts itself well in the manufacture of the instant beverages. The advantage is that the taste is not altered. Usually, extractions of coffee and tea are carried out at high temperatures which affect the tannin or tannic acid in the tea or coffee; as result the taste is altered. By imparting the cavitation effect to the water containing tea leaves or ground coffee bean the meristematic tissue of the tea or coffee are ruptured and extract is thus obtained.

Reducing Facial Wrinkles.
The US patent 6113559 uses ultrasound to reduce facial skin wrinkles. The invention hypothesized that working ultrasound energy into the dermis layer triggers synthesis of new connective tissue through activation of fibroblast cells without damage. The connective tissue gives the dermis layer body, shape and support. Ultrasound includes the acoustic waves capable of inducing controlled cavitation in skin tissue. A cavitational bubble is generated and when the bubble collapses, a shock wave results that mechanically, in as localized area, tears apart tissue in the dermis causing dermal inflammation or irritation and the resultant synthesis of new connective tissue.

The US patent 5316591 uses cavitation to clean substrates. Here, the undesired material is removed by placing the substrate in chamber provided with cavitation-producing means and liquefied gas such the nontoxic carbon dioxide. The contaminants are taken up in liquid gas and then removed. The cavitation is produced by a transducer that produces energy such as a sonicating horn, propeller or cavitation nozzle. In such a cavitation nozzle, a bubble is created in the liquid by lowering the hydrodynamic pressure of the liquid below the vapor pressure of the liquid. The bubble then collapses when the pressures equilibrate. This collapse produces very high pressures that, in turn, produce shock waves.

Wound Treatment.
In the US patent 6478754 a wound surface is treated by using ultrasonic waves. One application of this method is the facilitation of dissolution of blood clots by using an ultrasound tip directed to a blood vessel with clot(s). The ultrasound standing waves create cavitation inside blood vessel and dissolve the clots.

(1) Sergio Lebid, SVP & Co-Founder, NanoSpire Inc.
(2) See, Jean-Pierre Franc and Jean-Marie Michel, FUNDAMENTALS OF CAVITATION (Dordrecht; Boston : Kluwer Academic Publishers, 2004).
(3) For general background,

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