Electromagnetic radiation generated by electrospinning Petr Mikeš David Lukáš, Pavel Pokorný Technical University of Liberec Czech Republic

What is electrospinning

Pavel’s observation of strange pulses Strength of electrostatic field on the top of Taylor's cone can rise up to GV/m. Observation of some radiation by medical X-ray sensitive film.

Online measurement by GM tube did not detect any radiation but ...SURPRISE F18(1.83h)‏ C11 (20.4m)‏ Cl34 (32m)‏

Is this exponential dependance caused by desorption ? ???Questions??? Is this exponential dependance caused by desorption ? NO !!!

Is it temperature dependant? NO !!! It has to be somehow releated with nucleus !!!

Radon daughter deposition on electrostatically charged surfaces Measurement by Geiger – Muller detectror Radiant energy ranges of Gamma-radiation: from 0,06 to 1,2 MeV Radiant energy ranges of Beta-radiation: from 0,5 to 3 MeV Background level

Energy dispersive X-ray analysis Is it possible to use nanofibrous naterials for medical aplications due to Pb210 deposition? Energy dispersive X-ray analysis No problem

Radon daughter deposition on electrostatically surfaces However, the pathways linking radon radioactivity to living tissues are not direct. Once deposited on the surface of living tissue, the daughter decay can cause biological damage. The radon daughters have an affinity for negatively charged surfaces. The mechanism for this behavior is related to the fact that radon daughters tend to be produced with a positive charge as a result of the stripping of electrons from the parent atom during radioactive decay. The human body often carries a negative static charge.

More samples

Are the tracks really made by radon progeny? We didn’t observe any tracks without polymer and during electrospraying Tracks cannot be made by radon daughters With another experiments we found similarity of tracks with fiber’s deposition

Experimental setup Setup with parallelized nanofibers Classical setup We found tracks on radiographic film even for sample with parallelized nanofibers

Theoretical predictions Which is the area of soft Simple calculation Which is the area of soft X-ray radiation c = 100 mm r = 100 nm Emax= 21.6 GV/m => Wk= Emax . d . s = 1.4 keV

Spectrum measurement needed

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Electromagnetic spectrum of radiation 30kV/100 mm 30kV/100 mm 7,5kV/25 mm 15kV/50 mm If we are talking about nanofibres, we have to include quantum mechanics into it

RESULTS SOFT X-rays HARD X-rays

EXAMPLE 1 the maximum field strength is estimated as 39 GV/m

EXAMPLE 2 The predicted field strength enables electrons and ions, having the elementary charge e, to reach over the distance of 100 nm a kinetic energy about 0.0095 keV, which is about three orders less than the maximal X-ray energy in measured spectra

Theoretical background Poisson – Boltzmann theory Distribution of ions charge density Poisson-Boltzmann equation

For small exponent and by using of first Maxwell equation (Gauss law) Debye- Hückel limiting law Debye’s length For large numbers of ions

Where b is average spacing between charges on the fiber It is helpful to implement another parameter called Bjerrum length dimensionless Manning parameter Where b is average spacing between charges on the fiber Poisson - Boltzmann equation Substitution of nondimensionless potential and by using of cylindrical coordinates Solution

Approximation for charges of only one sign This roughly estimated mean field strength value inside the Manning region is about 150 GV/m Therefore the theoretically predicted field strength enables electrons to reach over the short distance x=100nm a massive kinetic energy, which is about 15 keV

Current setup

Take up and twisting setup Preparation for twisting Parallelization Take down Preparation for twisting Twisting Produced yarn Storing

PVA PVDF

Yarn 1 Yarn 2 Yarn 3 Yarn 1 Yarn 2 Yarn 3 Yarn 4 Time used for El.spinning t [s] 300 Average diameter d [um] 31.8 32.1 27.7 26.5 Standard deviation [um] 1.6 3.6 1.8 3.1 Yarn 2 Yarn 3

SIOUX III