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Electrospinning is a fiber production method that uses electrical force (based on electrohydrodynamic principles) to draw charged threads of
polymer solution Polymer solutions are solutions containing dissolved polymers. These may be (e.g. in ), or solid solutions (e.g. a substance which has been plasticized). The introduction into the polymer of small amounts of a solvent (plasticizer) reduces the te ...
s for producing nanofibers with diameters ranging from nanometers to micrometers. Electrospinning shares characteristics of both
electrospray The name electrospray is used for an apparatus that employs electricity to disperse a liquid or for the fine aerosol resulting from this process. High voltage is applied to a liquid supplied through an emitter (usually a glass or metallic capilla ...
ing and conventional solution dry spinning of fibers.Ziabicki, A. (1976) ''Fundamentals of fiber formation'', John Wiley and Sons, London, . The process does not require the use of coagulation chemistry or high temperatures to produce solid threads from solution. This makes the process particularly suited to the production of fibers using large and complex molecules. Electrospinning from molten precursors is also practiced; this method ensures that no
solvent A solvent (from the Latin language, Latin ''wikt:solvo#Latin, solvō'', "loosen, untie, solve") is a substance that dissolves a solute, resulting in a Solution (chemistry), solution. A solvent is usually a liquid but can also be a solid, a gas ...
can be carried over into the final product.


Process

When a sufficiently high
voltage Voltage, also known as (electrical) potential difference, electric pressure, or electric tension, is the difference in electric potential between two points. In a Electrostatics, static electric field, it corresponds to the Work (electrical), ...
is applied to a liquid droplet, the body of the liquid becomes charged, and
electrostatic repulsion Electrostatics is a branch of physics that studies slow-moving or stationary electric charges. Since classical times, it has been known that some materials, such as amber, attract lightweight particles after rubbing. The Greek word (), meani ...
counteracts the
surface tension Surface tension is the tendency of liquid surfaces at rest to shrink into the minimum surface area possible. Surface tension (physics), tension is what allows objects with a higher density than water such as razor blades and insects (e.g. Ge ...
and the
droplet A drop or droplet is a small column of liquid, bounded completely or almost completely by free surfaces. A drop may form when liquid accumulates at the end of a tube or other surface boundary, producing a hanging drop called a pendant drop. Dro ...
is stretched; at a critical point a stream of liquid erupts from the surface. This point of eruption is known as the Taylor cone. If the molecular cohesion of the liquid is sufficiently high, stream breakup does not occur (if it does, droplets are electrosprayed) and a charged liquid jet is formed. As the jet dries in flight, the mode of current flow changes from ohmic to convective as the charge migrates to the surface of the fiber. The jet is then elongated by a whipping process caused by
electrostatic Electrostatics is a branch of physics that studies slow-moving or stationary electric charges. Since classical times, it has been known that some materials, such as amber, attract lightweight particles after rubbing. The Greek word (), mean ...
repulsion initiated at small bends in the fiber, until it is finally deposited on the grounded collector.High speed video of the whipping instability
youtube.com
The elongation and thinning of the fiber resulting from this bending instability leads to the formation of uniform fibers with
nanometer 330px, Different lengths as in respect to the Molecule">molecular scale. The nanometre (international spelling as used by the International Bureau of Weights and Measures; SI symbol: nm), or nanometer (American spelling Despite the va ...
-scale diameters.


Parameters

Source: * Molecular weight, molecular-weight distribution and architecture (branched, linear etc.) of the polymer * Solution properties (viscosity, conductivity, and surface tension) * Electric potential, flow rate and concentration * Distance between the capillary and collection screen * Ambient parameters (temperature, humidity and air velocity in the chamber) * Motion and size of target screen (collector) * Needle gauge


Apparatus and range

The standard laboratory setup for electrospinning consists of a
spinneret A spinneret is a silk-spinning organ of a spider or the larva of an insect. Some adult insects also have spinnerets, such as those borne on the forelegs of Embioptera. Spinnerets are usually on the underside of a spider's opisthosoma, and ar ...
(typically a
hypodermic syringe A syringe is a simple reciprocating pump consisting of a plunger (though in modern syringes, it is actually a piston) that fits tightly within a cylindrical tube called a barrel. The plunger can be linearly pulled and pushed along the insid ...
needle) connected to a high-voltage (5 to 50 kV) direct current power supply, a
syringe pump A syringe driver, also known as a syringe pump, is a small infusion pump, used to gradually administer small amounts of fluid (with or without medication) to a patient or for use in chemical and biomedical research. Some syringe drivers can both ...
, and a grounded collector. A
polymer A polymer () is a chemical substance, substance or material that consists of very large molecules, or macromolecules, that are constituted by many repeat unit, repeating subunits derived from one or more species of monomers. Due to their br ...
solution, sol-gel, particulate suspension or melt is loaded into the syringe and this liquid is extruded from the needle tip at a constant rate by a syringe pump. Alternatively, the droplet at the tip of the spinneret can be replenished by feeding from a header tank providing a constant feed pressure. This constant pressure type feed works better for lower viscosity feedstocks.


Scaling-up possibilities

* Alternating current electrospinning * Needleless (also known as, nozzle-free) electrospinning * Multiplying the needles * High-throughput roller electrospinning * Wire electrospinning * Bubble electrospinning * Ball electrospinning * High speed electrospinning * Plate edge electrospinning * Bowl electrospinning * Hollow tube electrospinning * Rotary cone electrospinning * Spiral coil electrospinning * Electroblowing


Other techniques

Modification of the spinneret and/or the type of solution can allow for the creation of fibers with unique structures and properties. Electrospun fibers can adopt a porous or core–shell morphology depending on the type of materials being spun as well as the evaporation rates and
miscibility Miscibility () is the property of two substances to mix in all proportions (that is, to fully dissolve in each other at any concentration), forming a homogeneous mixture (a solution). Such substances are said to be miscible (etymologically ...
for the solvents involved. For techniques which involve multiple spinning fluids, the general criteria for the creation of fibers depends upon the spinnability of the outer solution. This opens up the possibility of creating composite fibers which can function as drug delivery systems or possess the ability to self-heal upon failure.


Co-axial electrospinning

A coaxial setup uses a dual-solution feed system which allows for the injection of one solution into another at the tip of the
spinneret A spinneret is a silk-spinning organ of a spider or the larva of an insect. Some adult insects also have spinnerets, such as those borne on the forelegs of Embioptera. Spinnerets are usually on the underside of a spider's opisthosoma, and ar ...
. The sheath fluid is believed to act as a carrier which draws in the inner fluid at the Taylor Cone of the electrospinning jet. If the solutions are immiscible then a core shell structure is usually observed. Miscible solutions however can result in porosity or a fiber with distinct phases due to phase separation during solidification of the fiber. For more advanced setups, a triaxial or quadaxial (tetra-axial)
spinneret A spinneret is a silk-spinning organ of a spider or the larva of an insect. Some adult insects also have spinnerets, such as those borne on the forelegs of Embioptera. Spinnerets are usually on the underside of a spider's opisthosoma, and ar ...
can be used with multiple solutions.


Emulsion electrospinning

Emulsion An emulsion is a mixture of two or more liquids that are normally Miscibility, immiscible (unmixable or unblendable) owing to liquid-liquid phase separation. Emulsions are part of a more general class of two-phase systems of matter called colloi ...
s can be used to create core shell or composite fibers without modification of the spinneret. However, these fibers are typically more difficult to produce compared to coaxial spinning due to the greater number of variables which must be accounted for in creating the emulsion. A water phase and an immiscible solvent phase are mixed in the presence of an emulsifying agent to form the emulsion. Any agent which stabilizes the interface between the immiscible phases can be used. Surfactants such as
sodium dodecyl sulfate Sodium dodecyl sulfate (SDS) or sodium lauryl sulfate (SLS), sometimes written sodium laurilsulfate, is an organic compound with the formula and structure . It is an anionic surfactant used in many cleaning and hygiene products. This compound ...
,
Triton X-100 Triton X-100 (''n'') is a nonionic surfactant that has a hydrophilic polyethylene oxide chain (on average it has 9.5 ethylene oxide units) and an aromatic hydrocarbon lipophilic or hydrophobic group. The hydrocarbon group is a 4-( 1,1,3,3-tetr ...
and
nanoparticles A nanoparticle or ultrafine particle is a particle of matter 1 to 100 nanometres (nm) in diameter. The term is sometimes used for larger particles, up to 500 nm, or fibers and tubes that are less than 100 nm in only two directions. At ...
have been used successfully. During the electrospinning process the emulsion droplets within the fluid are stretched and gradually confined leading to their coalescence. If the
volume fraction In chemistry and fluid mechanics, the volume fraction \varphi_i is defined as the volume of a constituent ''V'i'' divided by the volume of all constituents of the mixture ''V'' prior to mixing: :\varphi_i = \frac . Being dimensionless quantit ...
of inner fluid is sufficiently high, a continuous inner core can be formed. Electrospinning of blends is a variation of this technique which uses the fact that polymers are generally immiscible with each and can phase segregate without the use of surfactants. This method can be simplified further if a solvent which dissolves both polymers is used.


Melt electrospinning

Electrospinning of polymer melts eliminates the need for volatile solvents in solution electrospinning. Semi crystalline polymer fibers such as PE,
PET A pet, or companion animal, is an animal kept primarily for a person's company or entertainment rather than as a working animal, livestock, or a laboratory animal. Popular pets are often considered to have attractive/ cute appearances, inte ...
and PP, which would otherwise be impossible or very difficult to create using solution spinning, can be created. The setup is very similar to that employed in conventional electrospinning and includes the use of a syringe or spinneret, a high voltage supply and the collector. The polymer melt is usually produced by heating from either resistance heating, circulating fluids, air heating or lasers. Due to the high viscosity of polymer melts, the fiber diameters are usually slightly larger than those obtained from solution electrospinning. The fiber uniformity upon achieving stable flow rates and thermal equilibrium, tends to be very good. The whipping instability which is the predominant stage in which the fiber is stretched for spinning from solutions can be absent from the process due to the low melt conductivity and high viscosity of the melt. The most significant factors which affect the fiber size tend to be the feed rate, the molecular weight of the polymer and the diameter of the spinneret. Fiber sizes ranging from ~250 nm to several hundreds of
micrometers The micrometre (Commonwealth English as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American English), also commonly known by the non-SI term micron, is a unit of length in the International System ...
have been created thus far with the lower sizes being achieved using low molecular weight polymers.


History

In the late 16th century William GilbertGilbert, W. (1628) De Magnete, Magneticisque Corporibus, et de Magno Magnete Tellure (On the Magnet and Magnetic Bodies, and on That Great Magnet the Earth), London, Peter Short. set out to describe the behavior of magnetic and electrostatic phenomena. He observed that when a suitably electrically charged piece of amber was brought near a droplet of water it would form a cone shape and small droplets would be ejected from the tip of the cone: this is the first recorded observation of
electrospray The name electrospray is used for an apparatus that employs electricity to disperse a liquid or for the fine aerosol resulting from this process. High voltage is applied to a liquid supplied through an emitter (usually a glass or metallic capilla ...
ing. In 1887
C. V. Boys Sir Charles Vernon Boys, Fellow of the Royal Society, FRS (15 March 1855 – 30 March 1944) was a British physicist, known for his careful and innovative experimental work in the fields of thermodynamics and high-speed photography, and as a pop ...
described ''“the old, but little known experiment of electrical spinning”''. Boys’ apparatus consisted of ''“a small dish, insulated and connected with an electrical machine”''. He found that as his stock liquid reached the edge of the dish, that he could draw fibers from a number of materials including
shellac Shellac () is a resin secreted by the female Kerria lacca, lac bug on trees in the forests of India and Thailand. Chemically, it is mainly composed of aleuritic acid, jalaric acid, shellolic acid, and other natural waxes. It is processed and s ...
,
beeswax Bee hive wax complex Beeswax (also known as cera alba) is a natural wax produced by honey bees of the genus ''Apis''. The wax is formed into scales by eight wax-producing glands in the abdominal segments of worker bees, which discard it in o ...
, sealing-wax,
gutta-percha Gutta-percha is a tree of the genus ''Palaquium'' in the family Sapotaceae, which is primarily used to create a high-quality latex of the same name. The material is rigid, naturally biologically Chemically inert, inert, resilient, electrically n ...
and
collodion Collodion is a flammable, syrupy solution of nitrocellulose in Diethyl ether, ether and Alcohol (chemistry), alcohol. There are two basic types: flexible and non-flexible. The flexible type is often used as a surgical dressing or to hold dressings ...
. The process of electrospinning was patented by J.F. Cooley in May 1900Cooley, J.F. Patent GB 06385 "Improved methods of and apparatus for electrically separating the relatively volatile liquid component from the component of relatively fixed substances of composite fluids" 19 May 1900 and February 1902 and by W.J. Morton in July 1902. In 1914
John Zeleny John Zeleny (March 26, 1872 – June 19, 1951) was an American physicist who, in 1911, invented the Zeleny electroscope. He also studied the effect of an electric field on a liquid meniscus. His work is seen by some as a beginning to emergent te ...
, published work on the behavior of fluid droplets at the end of metal capillaries. His effort began the attempt to mathematically model the behavior of fluids under electrostatic forces. Further developments toward commercialization were made by Anton Formhals, and described in a sequence of patents from 1934 to 1944 for the fabrication of textile yarns. Electrospinning from a melt rather than a solution was patented by C.L. Norton in 1936 using an air-blast to assist fiber formation. In 1938 Nathalie D. Rozenblum and Igor V. Petryanov-Sokolov, working in Nikolai A. Fuchs' group at the Aerosol Laboratory of the L. Ya. Karpov Institute in the USSR, generated electrospun fibers, which they developed into filter materials known as " Petryanov filters". By 1939, this work had led to the establishment of a factory in
Tver' Tver (, ) is a types of inhabited localities in Russia, city and the administrative centre of Tver Oblast, Russia. It is situated at the confluence of the Volga and Tvertsa rivers. Tver is located northwest of Moscow. Population: The city is ...
for the manufacture of electrospun smoke filter elements for gas masks. The material, dubbed BF (Battlefield Filter) was spun from
cellulose acetate In biochemistry, cellulose acetate refers to any acetate ester of cellulose, usually cellulose diacetate. It was first prepared in 1865. A bioplastic, cellulose acetate is used as a film base in photography, as a component in some coatings, and ...
in a solvent mixture of
dichloroethane Dichloroethane can refer to either of two isomeric organochloride Organochlorine chemistry is concerned with the properties of organochlorine compounds, or organochlorides, organic compounds that contain one or more carbon–chlorine bonds. The c ...
and
ethanol Ethanol (also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound with the chemical formula . It is an Alcohol (chemistry), alcohol, with its formula also written as , or EtOH, where Et is the ps ...
. By the 1960s output of spun filtration material was claimed as 20 million m2 per annum. Between 1964 and 1969 Sir Geoffrey Ingram Taylor produced the theoretical underpinning of electrospinning. Taylor’s work contributed to electrospinning by mathematically modeling the shape of the cone formed by the fluid droplet under the effect of an electric field; this characteristic droplet shape is now known as the Taylor cone. He further worked with J. R. Melcher to develop the "leaky dielectric model" for conducting fluids. Simon, in a 1988 NIH SBIR grant report, showed that solution electrospinning could be used to produce nano- and submicron-scale polystyrene and polycarbonate fibrous mats specifically intended for use as in vitro cell substrates. This early application of electrospun fibrous lattices for cell culture and tissue engineering showed that various cell types would adhere to and proliferate upon the fibers in vitro. Small changes in the surface chemistry of the fibers were also observed depending upon the polarity of the electric field during spinning. In the early 1990s several research groups (notably that of Reneker and Rutledge who popularised the name ''electrospinning'' for the process) demonstrated that many
organic Organic may refer to: * Organic, of or relating to an organism, a living entity * Organic, of or relating to an anatomical organ Chemistry * Organic matter, matter that has come from a once-living organism, is capable of decay or is the product ...
polymers could be electrospun into
nanofiber Nanofibers are fibers with diameters in the Nanometre, nanometer range (typically, between 1 nm and 1 μm). Nanofibers can be generated from different polymers and hence have different physical properties and application potentials. Examples ...
s. Between 1996 and 2003 the interest in electrospinning underwent an explosive growth, with the number of publications and patent applications approximately doubling every year. Since 1995 there have been further theoretical developments of the driving mechanisms of the electrospinning process. Reznik ''et al.'' described the shape of the Taylor cone and the subsequent ejection of a fluid jet. Hohman ''et al.'' investigated the relative growth rates of the numerous proposed instabilities in an electrically forced jet once in flight and endeavors to describe the most important instability to the electrospinning process, the bending (whipping) instability.


Uses

The size of an electrospun fiber can be in the nano scale and the fibers may possess nano scale surface texture, leading to different modes of interaction with other materials compared with macroscale materials.Ajayan P. M., Schadler, L. S. and Braun, P. V. (2003) Nanocomposite Science and Technology, Weinheim, Wiley-VCH, , . In addition to this, the ultra-fine fibers produced by electrospinning are expected to have two main properties, a very high surface to volume ratio, and a relatively defect free structure at the molecular level. This first property makes electrospun material suitable for activities requiring a high degree of physical contact, such as providing sites for chemical reactions, or the capture of small sized particulate material by physical entanglement – filtration. The second property should allow electrospun fibers to approach the theoretical maximum strength of the spun material, opening up the possibility of making high mechanical performance
composite materials A composite or composite material (also composition material) is a material which is produced from two or more constituent materials. These constituent materials have notably dissimilar chemical or physical properties and are merged to create a ...
.


Filtration and adsorption

The use of nanofiber webs as a filtering medium is well established. Due to the small size of the fibers London-Van Der Waals forces are an important method of adhesion between the fibers and the captured materials. Polymeric nanofibers have been used in air filtration applications for more than seven decades.Donaldson Nanofiber Products
Because of poor bulk mechanical properties of thin nanowebs, they are laid over a filtration medium substrate. The small fiber diameters cause slip flows at fiber surfaces, causing an increase in the interception and inertial impaction efficiencies of these composite filter media. The enhanced filtration efficiency at the same pressure drop is possible with fibers having diameters less than 0.5 micrometer. Since the essential properties of protective clothing are high moisture vapor transport, increased fabric breath-ability, and enhanced toxic chemical resistance, electrospun nanofiber membranes are good candidates for these applications. Given the high surface-to-volume ratio of electrospun nanofibers, they can also be used as relatively efficient adsorbents compared to micron-sized fibers. One way to achieve this is by mixing the electrospinning solution with suitable additives or by using active polymers. For example, iron oxide nanoparticles, a good arsenic adsorbent, can be trapped within poly(vinyl alcohol) electrospun nanofibers for water remmediation.


Textile manufacturing

The majority of early patents for electrospinning were for textile applications, however little woven fabric was actually produced, perhaps due to difficulties in handling the barely visible fibers. However, electrospinning has the potential to produce seamless non-woven garments by integrating advanced manufacturing with fiber electrospinning. This would introduce multi-functionality (flame, chemical, environmental protection) by blending fibers into electrospinlaced (using electrospinning to combine different fibers and coatings to form three-dimensional shapes, such as
clothing Clothing (also known as clothes, garments, dress, apparel, or attire) is any item worn on a human human body, body. Typically, clothing is made of fabrics or textiles, but over time it has included garments made from animal skin and other thin s ...
) layers in combination with
polymer A polymer () is a chemical substance, substance or material that consists of very large molecules, or macromolecules, that are constituted by many repeat unit, repeating subunits derived from one or more species of monomers. Due to their br ...
coatings.


Medical

Electrospinning can also be used for medical purposes. The electrospun scaffolds made for
tissue engineering Tissue engineering is a biomedical engineering discipline that uses a combination of cells, engineering, materials methods, and suitable biochemical and physicochemical factors to restore, maintain, improve, or replace different types of biolo ...
applications can be penetrated with cells to treat or replace biological targets. Nanofibrous
wound dressings A dressing or compress is a piece of material such as a pad applied to a wound to promote healing and protect the wound from further harm. A dressing is designed to be in direct contact with the wound, as distinguished from a bandage, which is mos ...
have excellent capability to isolate the wound from microbial infections. Other medical textile materials such as sutures are also attainable via electrospinning. Through the addition of a drug substance into the electrospinning solution or melt diverse fibrous drug delivery systems (e.g., implants, transdermal patches, oral forms) can be prepared. Electropsun propolis nanofibrous membrane showed an antiviral effect against the SARS-CoV-2 virus, and an antibacterial effect against Staphylococcus aureus and Salmonella enterica bacteria. Interestingly, electrospinning allows to fabricate nanofibers with advanced architecture that can be used to promote the delivery of multiple drugs at the same time and with different kinetics. Composite printing was explored by incorporating lignosulfonate into cellulose acetate, creating antibacterial properties.


Cosmetic

Electrospun nanomaterials have been employed to control their delivery so they can work within skin to improve its appearance. Electrospinning is an alternative to traditional nanoemulsions and nanoliposomes.


Pharmaceutical manufacturing

The continuous manner and the effective drying effect enable the integration of electrospinning into continuous pharmaceutical manufacturing systems. The synthesized liquid drug can be quickly turned into an electrospun solid product processable for tableting and other dosage forms.


Composites

Ultra-fine electrospun fibers show clear potential for the manufacture of long fiber composite materials. Application is limited by difficulties in making sufficient quantities of fiber to make substantial large scale articles in a reasonable time scale. For this reason medical applications requiring relatively small amounts of fiber are a popular area of application for electrospun fiber reinforced materials. Electrospinning is being investigated as a source of cost-effective, easy to manufacture wound dressings, medical implants, and scaffolds for the production of artificial human tissues. These scaffolds fulfill a similar purpose as the
extracellular matrix In biology, the extracellular matrix (ECM), also called intercellular matrix (ICM), is a network consisting of extracellular macromolecules and minerals, such as collagen, enzymes, glycoproteins and hydroxyapatite that provide structural and bio ...
in natural tissue. Biodegradable polymers, such as
polycaprolactone Polycaprolactone (PCL) is a synthetic, semi-crystalline, biodegradable polyester with a melting point of about 60 °C and a glass transition temperature of about −60 °C. The most common use of polycaprolactone is in the production ...
and
polysaccharide Polysaccharides (), or polycarbohydrates, are the most abundant carbohydrates found in food. They are long-chain polymeric carbohydrates composed of monosaccharide units bound together by glycosidic linkages. This carbohydrate can react with wat ...
s, are typically used for this purpose. These fibers may then be coated with
collagen Collagen () is the main structural protein in the extracellular matrix of the connective tissues of many animals. It is the most abundant protein in mammals, making up 25% to 35% of protein content. Amino acids are bound together to form a trip ...
to promote cell attachment, although collagen has successfully been spun directly into membranes. Transmission electron micrograph of electrospun poly(vinyl alcohol) nanofibers loaded with iron oxide nanoparticles. These nanoparticles can be used for the adsorption of water contaminants.


Catalysts

Electrospun fibers may have potential as a surface for
enzyme An enzyme () is a protein that acts as a biological catalyst by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different mol ...
s to be immobilized on. These enzymes could be used to break down toxic chemicals in the environment, among other things.


Mass production

Thus far, at least eight countries in the world have companies which provide industrial-level and laboratory-scale electrospinning machines: three companies each in
Italy Italy, officially the Italian Republic, is a country in Southern Europe, Southern and Western Europe, Western Europe. It consists of Italian Peninsula, a peninsula that extends into the Mediterranean Sea, with the Alps on its northern land b ...
and
Czech Republic The Czech Republic, also known as Czechia, and historically known as Bohemia, is a landlocked country in Central Europe. The country is bordered by Austria to the south, Germany to the west, Poland to the northeast, and Slovakia to the south ...
, two each in
Iran Iran, officially the Islamic Republic of Iran (IRI) and also known as Persia, is a country in West Asia. It borders Iraq to the west, Turkey, Azerbaijan, and Armenia to the northwest, the Caspian Sea to the north, Turkmenistan to the nort ...
,
Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...
, and
Spain Spain, or the Kingdom of Spain, is a country in Southern Europe, Southern and Western Europe with territories in North Africa. Featuring the Punta de Tarifa, southernmost point of continental Europe, it is the largest country in Southern Eur ...
, and one each in the
Netherlands , Terminology of the Low Countries, informally Holland, is a country in Northwestern Europe, with Caribbean Netherlands, overseas territories in the Caribbean. It is the largest of the four constituent countries of the Kingdom of the Nether ...
,
New Zealand New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...
, and
Turkey Turkey, officially the Republic of Türkiye, is a country mainly located in Anatolia in West Asia, with a relatively small part called East Thrace in Southeast Europe. It borders the Black Sea to the north; Georgia (country), Georgia, Armen ...
.


References


Further reading

* * * * * * {{refend


External links


Polish Academy of Science's page on electrospinning

How to describe the electrospinning process

Hackaday, "OpenESpin Building an Electrospinning machine for everyone."


* ttps://spingenix.com/ Electrospinning Industrial processes Nanotechnology Spinning