Tomasz Ciach PhD Eng. Professor
 
Beata Butruk-Raszeja PhD Eng.
 
Magdalena Janczewska MSc Eng.
 
Katarzyna Każmierska MSc Eng.
Kamil Kopeć MSc Eng.
 
Piotr Kowalczyk MSc Eng.
 
Martyna Kucharska PhD Eng.
 
Aleksandra Kuźmińska, MSc Eng.
 
Aleksandra Kulikowska MSc Eng.
 
Ilona Łojszczyk MSc Eng.
 
Aleksandra Mościcka-Studzińska MSc Eng.
 
Rafał Podgórski MSc Eng.
 
Aleksandra Poniatowska MSc Eng.
 
Agata Stefanek MSc Eng.
 
Paulina Trzaskowska MSc Eng.
 
Maciej Trzaskowski MSc Eng.
 

Iga Wasiak MSc Eng.

 
Michał Wojasiński MSc Eng.
 

 

Electrostatic Spraying

ZThe phenomenon of electrostatic spraying was probably already observed by ancient Greeks who carried out a lot of experiments with electrically charged amber. When a droplet of liquid is subjected to strong electric field, due to mutual repulsion of electrical charges inside the droplet, it change its shape to conical. If the electric field is strong enough, from the cone apex a thin liquid jet emerges, which quickly breaks up into the mist of fine droplets. The first known to me publication about this phenomenon appeared in 1600. It was a book by William Gilbert of Colchester titled “De Magnete”. To avoid confusion with other spraying techniques also employing electrostatics together with other means to produce droplets, definition of Electro Hydro Dynamic Atomization (EHDA) method that employs only electrostatics, is recommended..

If we spray this way solution of a solid substance, after solvent evaporation we obtain solid particles of the diameter from nanometres to hundreds of micrometers (depending on the spraying conditions), and of narrow size distribution. When a solution of fibre forming polymer is sprayed by EHDA, we obtain fibres of nanometre to micrometer sizes, this process is called electrospinning and is described elsewhere in this wedpage.

Particles Production by EHDA:

Due to the unique properties of EHDA process it recently became a topic of research in many laboratories. Produced particles can be porous, or shell like showing very high porosity applicable in pulmonary drug delivery, they can be made of biobegradable polymers and contain drugs which are released over a few weeks time. Typical setup for particles production is shown below..

When we want to harvest obtained particles Electrostatic Atomization should be performed in the special chamber. The setup consists of a cylindrical glass tube with tapered ends. One end acts as an inlet for filtered air and the other end ducts the produced particles via a heater to the collection side. The heating, after which the produced particles are captured on a filter, is necessary to evaporate the solvent. Normally, organic solvents, such as dichloromethane or acetone evaporate very quickly especially in the form of small droplets but if the polymer is present in the solution, a jelly outer layer is formed, which slows down the evaporation drastically. The EHDA spraying nozzle is positioned in a glass side tube in which also the counter electrode ring is placed close to the main glass cylinder. Discharge needle is inserted in the glass cylinder opposite to the spraying nozzle. Since the produced droplets are highly charged they have to be discharge to avoid Rayleigh explosion due to mutual repulsion of electrical charges. Particles are collected on a membrane filter placed downstream of the set-up. Air is drawn through the filter by a vacuum pump maintaining a small under-pressure in the spraying chamber. Solution which we spray should have electrical conductivity from 10-9 to 10-5 S/m. Disadvantage of the EHDA particle production technique is a low production rate, advantages are wide droplet size range together with a narrow size distribution, simplicity and gentleness.

More information:

Publications:

  • Ciach T., Application of Electro Hydro Dynamic Atomization in Drug Delivery, Journal of Drug Delivery Science and Technology, vol. 17, No 6, p. 367-375, 2007.
  • Ciach T., Microencapsulation of drugs by electro-hydro-dynamic atomization, International Journal of Pharmaceutics, 324, 51-55, 2006.
  • Ciach T., Otrzymywanie cząstek do kontrolowanego uwalniania leków, Inżynieria Chemiczna i Procesowa, Vol 25, 795-801, 2004.
  • Ciach T., Diaz L., Ijsel E., Marijnissen J., Application of electro hydro dynamic atomization in the production of engineered drug particles, rozdział w ksoążce: Optimization of Aerosol Drug Delivery, Kluwer Academic Publishers 2003.
  • Ciach T., Geerse K.B., Marijnissen J.C.M., Chapter in the book: Nanostructured materials, Application of electrospray in nanoparticle production, edited by P. Knauth, J. Shoonman, Kluwer Academic Publishers, 2002.
  • Ciach T., Marijnissen J., Electro-hydro-dynamic atomisation of polymers, J. Aerosol Sci., vol. 32, S1003, 2001
  • Ciach T., Wang J., Marijnissen J., Production of protein loaded microparticles by EHDA, J. Aerosol Sci., vol. 32, s1, 1001, 2001

 

 
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