One of MGM’s techniques is micoencapsulation process, which consists in coating tiny fluid drops or gas bubbles or small amounts of solids with a thin film, usually made of natuaral or syntetical polimers, in order to form granules.
This process is used in different areas, sush as industry and sub-categories.

WE EXPLOIT THE CAPACITIES OF PIEZOELECTRICITY

We exploit the capacities of piezoelectricity, a natural phenomenon that occurs in some substances in the crystalline state, such as silicon (S102), commonly known as quartz. The most updated techniques for generating vibration use mechanical fluctuations as frequencies over 18000 Hz, they are based on the use of piezoelectric ceramics such as titan and lead zirconate or a mixture of them.

Through an electrical voltage alterating over two faces of a piezoelectric chip made of ceramic, it can be possible to obtain an accumuation and expansion of the material. Throug a metallic structure that capture a piezoelectric device, it is possible to obtain a transdcer that, powered by its generator, converts electricity in mechanical energy. The transducer is connected to an the Booster, that work sas an amplitude amplifier.

The booster is connected to a Sonotrode, that transmits the energy we need. Transducer-booster-sonotrode constitute the vibrant group, they are built mechanically with high-elastic materials that can resist to intensive efforts, with a size between 25 and 60 u. Tthanks to the use of special alloys in aluminium and titano, equipements like these represent ideal means for energy transmission in the form of fluctuations. The trasducer generates mechanical fluctuations with determinated amplitude and frequencies, that can be employed in a wide range of industrial processes.

NEBULISATION AND MICROENCAPSULATION

If we pour a drop of fluid on a plate made of piezo-ceramic material in resonance, the acceleration that it impresses on the fluid is higher than the force of coherence of the fluid, causing the nebulisation of the fluid, as a sort of “cold boiling”.
Thanks to the studies done on this phenomenon, a lot of applications have been realized, such as the ultrasound nebulizers, used in the field of medicine, in particular for the aerosol therapy. To obtain this kind of nebulisations we have to apply high frequencies (about 1-2 Mhz).
If we use low frequencies, we will obtain bigger drops (diameter of a few hundreds of m) that permit the realization of the microencapsulation phenomenon.
It has been developed a unit of nebulisation that can be applied to both the two processes of microencapsulation, that are:
Spray Congealing, where the cover material has a low melting point, to which the material, or the active ingredient that has to be preserved, is dispersed; by atomizing the mixture obtained and giving time to the microspheres to come back to the solid state, we can obtain some grains of active ingredient that are completely covert with a material that has a low melting point. The final product is a set of microspheres with a perfectly geometrical form and highly sliding.
Spray Drying, in case the cover mixture is made by a liquid solution in which the active ingredient is disperse. The micro drops obtained have to be dried with special equipments.
The microencapsulation unit is composed by a power generator, generally to 20 KHz, which leads the vibrating group: transducer, booster e sonotrode.
On the final part of the sonotrode, it is applied a support made of stainless hardened steel, to which it is connected on the crucial point, in order not to interfere with the mechanical vibration of the sonotrode.
Generally, in the microencapsulation are used low-melting materials, such as waxes, whose melting points go from 45°C and 75÷80°C. That’s why it is necessary to maintain these temperatures both on the final part of the sonotrode and on the part used to transfer the fluid. This is possible thanks to a double-walled device, in which flows a heating fluid, generally water, and whose internal wall is a conveyor for the low-melting material that has to be nebulised.

THE MICROENCAPSULATION UNITY

The final part of the conveyor is interchangeable because the aperture where the fluid that has to be nebulised flows must be proportioned to the density and viscosity of the same fluid, but also because its dimension influences the diameter of the drops that generally goes between 100 and 300 µ.
By passing down the particles obtained from the nebulisation (using liquid nitrogen’s gas) in a cold place, a heat exchange occurs in an extremely easy way because the nebulised material, thanks to the gas’ action, presents a very large surface and therefore the exchange speed significantly increases.
The advantage of the use of ultrasounds is that, as they don’t have kinetics, it is possible to reduce the dimensions of the cell and, accordingly, to work with small-scale and economically viable equipment.
The heating fluid, used when there are low-melting products, fills the container’s over-wrap and flows thanks to a pump. This prevents the low-melting material from coming across cold areas and solidifying. Into the chamber there is a product collecting system.
On the internal sides of the chamber, there are some nozzles that feed the nitrogen’s gas into the chamber. External control devices permit to control both the temperature of the heating fluid and the internal temperature of the chamber. As the drops, when they solidify, have a perfect spherical form, the result is an extremely flowing powder that can be easily collected.

Depending on the kind of atomised material, the next step of this process can be divided into three proceedings:

  • Spray Congealing. Brackets with a low melting point are used in this process. The product is collected on the bottom of the cell and carried out in an automatic and continuous way: the product is ready for its final use.
  • Spray Drying. The product collected in the cell can be sent to a drying unit (lyophilizer) that permits a low temperature sublimation and possibly, the solvent recovery. If we use thermolabile active ingredients, it can create very good conditions to work in cold terms in a controlled atmosphere.
  • The third proceeding consists of the treatment of solid or liquid products that have to be microencapsulated in matrices made with fat materials with a variable melting point that, covering the entire product, solidify it at room temperature.

These technologies are particularly interesting both in the pharmaceutical field and in the alimentary one, but also for fitofarmacies.
For example, medicinal products’ active ingredients can be protected thanks to this technology, but it can also make highly toxic materials usable.
For what concerns alimentary products, the freezing or solidifying action is done by an inert gas, so that the organoleptic properties of the product won’t be altered. The microspheres obtained are extremely small.

+ NEBULISATION

NEBULISATION AND MICROENCAPSULATION

If we pour a drop of fluid on a plate made of piezo-ceramic material in resonance, the acceleration that it impresses on the fluid is higher than the force of coherence of the fluid, causing the nebulisation of the fluid, as a sort of “cold boiling”.
Thanks to the studies done on this phenomenon, a lot of applications have been realized, such as the ultrasound nebulizers, used in the field of medicine, in particular for the aerosol therapy. To obtain this kind of nebulisations we have to apply high frequencies (about 1-2 Mhz).
If we use low frequencies, we will obtain bigger drops (diameter of a few hundreds of m) that permit the realization of the microencapsulation phenomenon.
It has been developed a unit of nebulisation that can be applied to both the two processes of microencapsulation, that are:
Spray Congealing, where the cover material has a low melting point, to which the material, or the active ingredient that has to be preserved, is dispersed; by atomizing the mixture obtained and giving time to the microspheres to come back to the solid state, we can obtain some grains of active ingredient that are completely covert with a material that has a low melting point. The final product is a set of microspheres with a perfectly geometrical form and highly sliding.
Spray Drying, in case the cover mixture is made by a liquid solution in which the active ingredient is disperse. The micro drops obtained have to be dried with special equipments.
The microencapsulation unit is composed by a power generator, generally to 20 KHz, which leads the vibrating group: transducer, booster e sonotrode.
On the final part of the sonotrode, it is applied a support made of stainless hardened steel, to which it is connected on the crucial point, in order not to interfere with the mechanical vibration of the sonotrode.
Generally, in the microencapsulation are used low-melting materials, such as waxes, whose melting points go from 45°C and 75÷80°C. That’s why it is necessary to maintain these temperatures both on the final part of the sonotrode and on the part used to transfer the fluid. This is possible thanks to a double-walled device, in which flows a heating fluid, generally water, and whose internal wall is a conveyor for the low-melting material that has to be nebulised.

+ FUNCTIONALITY

THE MICROENCAPSULATION UNITY

The final part of the conveyor is interchangeable because the aperture where the fluid that has to be nebulised flows must be proportioned to the density and viscosity of the same fluid, but also because its dimension influences the diameter of the drops that generally goes between 100 and 300 µ.
By passing down the particles obtained from the nebulisation (using liquid nitrogen’s gas) in a cold place, a heat exchange occurs in an extremely easy way because the nebulised material, thanks to the gas’ action, presents a very large surface and therefore the exchange speed significantly increases.
The advantage of the use of ultrasounds is that, as they don’t have kinetics, it is possible to reduce the dimensions of the cell and, accordingly, to work with small-scale and economically viable equipment.
The heating fluid, used when there are low-melting products, fills the container’s over-wrap and flows thanks to a pump. This prevents the low-melting material from coming across cold areas and solidifying. Into the chamber there is a product collecting system.
On the internal sides of the chamber, there are some nozzles that feed the nitrogen’s gas into the chamber. External control devices permit to control both the temperature of the heating fluid and the internal temperature of the chamber. As the drops, when they solidify, have a perfect spherical form, the result is an extremely flowing powder that can be easily collected.

+ FINAL PHASE

Depending on the kind of atomised material, the next step of this process can be divided into three proceedings:

  • Spray Congealing. Brackets with a low melting point are used in this process. The product is collected on the bottom of the cell and carried out in an automatic and continuous way: the product is ready for its final use.
  • Spray Drying. The product collected in the cell can be sent to a drying unit (lyophilizer) that permits a low temperature sublimation and possibly, the solvent recovery. If we use thermolabile active ingredients, it can create very good conditions to work in cold terms in a controlled atmosphere.
  • The third proceeding consists of the treatment of solid or liquid products that have to be microencapsulated in matrices made with fat materials with a variable melting point that, covering the entire product, solidify it at room temperature.

These technologies are particularly interesting both in the pharmaceutical field and in the alimentary one, but also for fitofarmacies.
For example, medicinal products’ active ingredients can be protected thanks to this technology, but it can also make highly toxic materials usable.
For what concerns alimentary products, the freezing or solidifying action is done by an inert gas, so that the organoleptic properties of the product won’t be altered. The microspheres obtained are extremely small.