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

2. What is electrospinning

3. 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.

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

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

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

7. 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

8. 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

9. 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.

10. More samples

11. 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

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

13. 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

14. Spectrum measurement needed

15. SLP Series Silicon Lithium-Drifted [Si(Li)]
Planar Low-Energy X-Ray Detectors
Prof. Tomáš Čechák
FJFI, ČVUT – Prague
Premium performance spectroscopy from 1 keV to 30 keV
Superior resolution performance at low and high count rates
Multi-detector arrays available for use at fusion facilities
Thin Be window
High peak-to-background ratio
PopTop flexibility

16. 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

17. RESULTS
SOFT X-rays HARD X-rays

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

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

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

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

22. 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

23. 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

26. Current setup

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

28. PVA
PVDF

29. 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

30. SIOUX III