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

What is electrospinning

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. Pavel’s observation of strange pulses

Online measurement by GM tube did not detect any radiation but...SURPRISE C 11 (20.4m)‏ F 18 (1.83h)‏ Cl 34 (32m)‏

???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 Background level 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

Is it possible to use nanofibrous naterials for medical aplications due to Pb 210 deposition? Energy dispersive X-ray analysis

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

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

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

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

Spectrum measurement needed

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Electromagnetic spectrum of radiation If we are talking about nanofibres, we have to include quantum mechanics into it

SOFT X-rays HARD X-rays RESULTS

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

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 keV, which is about three orders less than the maximal X-ray energy in measured spectra EXAMPLE 2

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

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

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 ParallelizationTake down TwistingStoring Preparation for twisting Produced yarn

PVA PVDF

Yarn 1 Yarn 2 Yarn 3 Yarn 1Yarn 2Yarn 3Yarn 4 Time used for El.spinning t [s] 300 Average diameter d [um] Standard deviation [um]

SIOUX III