Yes, It's A Homogenizer — But Not Really
Microfluidizer® Processor Technology
For High Performance Mixing and Dispersion

In process-driven product applications such as chemicals, foods, personal care products, and pharmaceuticals, researchers are constantly looking for new ways to optimize existing formulations and to create new products.  Combinatorial chemistry, computer aided molecular design and biotechnology are three highly visible approaches for creating the new “wonder products” ranging from virus killers to fat substitutes.  But over the last 20 years researchers have also made progress on another front – one that is receiving growing attention.  It is the process of physically reducing particles into uniform submicron and nanometer particle sizes and dispersing them uniformly in a liquid.

High performance mixing and dispersion applications include:

• emulsification
• dispersion
• encapsulation/liposomes
• deagglomeration

All are different names for basically the same thing – increasing the commercial value of formulations by applying mechanical energy to them. For example:

• If you can make carbon particles (the pigment in inks) small enough (and create a dispersion stable enough) you can propel them through tiny jets and make possible the high resolution ink jet printer.
• If you make the size of fat globules in milk products small enough, you can reduce the fat content while improving taste (mouth feel) and increasing product stability and shelf life.
• If you encapsulate drug molecules within liposomal vesicles, the drug can be administered at lower dosage, with less toxicity, and with more precise targeting inside the human body—thereby reducing both costs and potentially harmful side effects.

So what has happened to make these advances possible? A trademarked and patented product of Microfluidics, Microfluidizer processor technology does what homogenizers, grinding mills, and other traditional “shake and break” products have done for over a century. The difference is this:  Many formulations produced using Microfluidizer® processor technology are either not possible, or not economical using conventional techniques. 

The advantages of Microfluidizer processor technology include:

• Much smaller particle and droplet size
• Much more uniform particle and droplet size distribution
• Faster processing times (>2 orders of magnitude in some applications)
• Better control of the amount of energy applied
• Much higher energy (up to 40,000 psi sustained)
• Scalability from small batches to continuous production
• No moving parts in the patented interaction chamber
• Easy to clean in many applications
• Little or no contamination
• Uniform and stable dispersions and emulsions
• Highly repeatable process from run to run or batch to batch

The reasons why these advantages are important depend on the application.  It is the ability, for example, to produce very small, very uniform particles in a few short batch runs that makes the ink jet application economical.  Alternative approaches, such as ball milling, would require weeks to yield carbon particles of similar size and consistency. In pharmaceuticals, it is the lack of contamination and the ability to uniformly disperse an active agent throughout its delivery media (e.g., water) that makes Microfluidizer processor technology the method of choice.

A Better approach

While the implementation details of Microfluidizer processor technology are proprietary, the overall principles are, as just noted, widely published and, in fact, fairly straightforward.  Perhaps the best way to understand Microfluidizer® processor technology is to compare it with more traditional methods for reducing particle size such as a grinding mill.  A grinding mill makes an appropriate point of comparison for two reasons.  First, it is the most widely used and therefore understood method of reducing particle size for materials which are to be dispersed; and, second, it may well be the oldest method known.

In a grinding mill, the material (a liquid, slurry, or powder) that is to be processed is combined with a media—such as ceramic beads—so that, as the mill rotates, the media grinds the material into smaller and smaller particles.  Grinding mills have been used for decades and the basic technology has remained the same.  Limitations of grinding mills include:

• Contamination of the product by the grinding media
• Difficulty scaling up the process
• Lacks control in the amount of energy applied
• Large batches require large (room size or bigger) mills
• Very long processing times are usually required to achieve small particle sizes
• High support requirements (cleaning, set up, extracting the media, etc.)

It might not be obvious why mills do not scale well.  Larger can be used for larger batches.  The problem is that the variables involved (mill size, media volume, product volume, media size, processing time) do not have a linear relationship.  Even though a process has been successfully prototyped, taking the process to a larger size mill may require extensive experimentation,in a sense re-prototyping the process a second time.

Another alternative to Microfluidizer processor technology is homogenizer valves which push fluids through a variable geometry spring loaded valve.  Like mills, homogenizers have also been used for many decades. They offer simplicity of operation and reliable service (at pressures typically below 10,000 psi). Their main drawback is limited particle size reduction – although they are adequate for less demanding applications requiring high volume throughput at low pressure such as milk homogenization at 2000 to 3000 psi.  A major limitation of the typical homogenizer is the spring actuated valve controlling the orifice size in response to the size of the particles passing through. This creates two potential problems:  Particle (or droplet) size is allowed to vary, and the process pressure is limited. In many cases, the results are less than satisfactory for demanding applications

All Microfluidizer processors have either a pneumatic, or electric-hydraulic intensifier pump, depending on the model selected. During processing, the product stream accelerates to very high velocities, creating shear rates within the product stream that are orders of magnitude greater than any other conventional means. The entire batch experiences identical processing conditions, producing the desired results, including: uniform particle and droplet size reduction (often submicron), deagglomeration and high yield cell disruption.

Constant pressure, uniformly applied, yields particles of uniform size distribution. High pressure, high velocity, and a variety of forces all working at once on the same fluid stream yield very small particles. A very broad pressure range (up to 40,000 psi) opens a wide variety of applications and materials to the advantages of small and uniform particle size distribution. These are the main advantages of Microfluidizer processor technology over traditional homogenizers and often the main advantages manufacturers look for when selecting technology to emulsify, deagglomerate, disperse or to accomplish cell disruption. But there are other advantages too; advantages that result as inherent byproducts of this new way to break down and mix materials.

The principles that enable Microfluidizer processor technology do not change whether the equipment is large or small. An application that has been developed, optimized and validated on a small machine can be migrated to incrementally larger machines as the market for that application grows.

Additional advantages are lower processing cost, increased speed of operation and more flexible manufacturing capability in the face of evolving market opportunities. 

What all these advantages add up to is this:  The Microfluidizer processor technology is not just another way to make an old formulation better — it is a new kind of process.  It opens up new opportunities in a variety of industries and markets that could not be pursued with the older technology — or would not have been economically viable.  Furthermore, the arrival of this technology is coincident with an upsurge of new applications in biotechnology, chemistry, food processing, pharmaceuticals, and other areas where progress depends on the ability to achieve the results only now possible with the Microfluidizer processor.

The “easy” applications have already been done.  It is the “hard” applications—the ones in which Microfluidizer processor technology demonstrates a genuine advantage—that will change the quality of life for consumers, open new markets to manufacturers, and generate real returns for investors.

®Microfluidizer is a registered trademark of Microfluidics.

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