Visualization of the Electrical Field in the Vicinity of a THz Pulse Exposed Cell with FDTD Simulation

Visualization of the Electrical Field in the Vicinity of a
THz Pulse Exposed Cell with FDTD Simulation
Aki Fujita
Science & Technology Inst., Co.
URL : https://www.kagiken.co.jp
Mail : cs_staff@kagiken.co.jp

2
Bioelectrics
Bioelectrics, a new multidisciplinary field encompassing
engineering and biology with applications to the medical,
environmental, food, energy, and biotechnological fields. 1)
Science & Technology Inst., Co. 2018-08-04
Visualization of the Electrical Field in the Vicinity of a THz Pulse Exposed Cell with FDTD Simulation ＠PIERS in Toyama
1)Bioelectrics @2017 ISBN 978-4-431-56095-1
Especially electromagnetic engineering

3
Charging Electrical Field with Electrode
2) Spatio-temporal dynamics of calcium electrotransfer during
cell membrane permeabilization
Guionet, Alexis; Moosavi Nejad, S.; Teissié, Justin; Sakugawa,
Takashi; Katsuki, Sunao; Akiyama, Hidenori; Hosseini, Hamid
Drug Delivery and Translational Research , Volume OnlineFirst
– May 11, 2018
✓ Pair of electrodes is needed and this
is demerit in vivo application
✓ Analytical prediction of Ca2+
permeabilization angle are
advocated by recent study2)

4
Charging Electrical Field by Traveling Pulse
✓ No electrodes are needed and this is
a merit in vivo application
✓ Though analytical prediction is
difficult, FDTD simulations are
suitable (THz wave length have
alomost the same figure as the
scale of cells)
✓ Dielectric properties vary
corresponding to pulse width, in
water absorptive for wide pulse and
transimissive for narrow pulse
This study treats this kind of system

5
3 Points of This Study
✓ Dielectric properties for water and intracellular water (ICW)
✓ 3 kinds of Gaussian pulse
✓ 3 shapes for cell and 2 polarization direction

6
Dielectric Properties for THz Wave
✓ ε’ for ICW is a little higher than that for sterilized water.
✓ ε” for ICW is a little lower than that for sterilized water.
✓ Effect by cytoplasm and cell organelle is small.

7
Dielectric Properties Modeling
In this study, we define the parameters as below.
𝜀’ 𝜔 = 𝑋1 + 𝑋2 + 𝑋3 + 𝜀’∞ =
𝛥𝜀’1
1 + 𝑗𝜔𝜏1
+
𝛥𝜀’2
1 + 𝑗𝜔𝜏2
+
𝐴 𝑠
𝜔𝑠
2
− 𝜔2 + 𝑗𝜔𝛾𝑠
+ 𝜀’∞
Debye-Debye-Lorentz model advocated by Ogawa et al.
Water ICW
ε’ at Infinete frequency ε′∞ 2.4 2.8
slow Debye dispersion Δε′1 74 58.5
τ1 7.3×10-12 6.8×10-12
fast Debye dispersion Δε′2 2.5 2.25
τ2 3.5×10-13 4.5×10-13
Lorentz dispersion As 1.15 1.1
ωs 2.8×1013 2.3×1013
γs 2.52×1013 2.07×1013

8
Governing Equations and Simulation Method
𝐻 𝑛+1 2 = 𝐻 𝑛−1 2 −
1
𝜇
𝛻 × 𝐸
𝐸 𝑛
=
𝜀∞
𝜀∞ + 𝛸0 𝐸 𝑛−1
+
1
𝜀∞ + 𝛸0
𝑚=0
𝑛−2
𝐸 𝑛−1−𝑚
∆𝛸 𝑚
+
∆𝑡 𝜀0
𝜀∞ + 𝛸0 𝛻 × 𝐻 𝑛−1 2
3. K.S.Kunz and R.J.Luebbers, The Finite Difference Time Domain
Method for Electromagnetics, Boca Taton,FL, CRC Press 1993
4. A.Taflove, Computational Electromagnetics, The Finite-Difference
Time-Domain Method, Norwood, MA, Artch House, 1995
Charge density term in Maxwell equation is expressed by time domain
recursive convolution of electric susceptibility X.

9
Simulation Models and Conditions
101×101×71 grids(Δx=Δy=Δz=2[μm])are applied and electrical field E ectors and magnetic field
vectors H are located on so-called staggered arrangement. Timestep is decided by the condition CFL
number = 0.5. In each case 1000 timesteps that corresponds 3.34×10-12[sec] are calculated.

10
Results
E-field on a plane of traveling pulse
1.03
0.97
1.03
0.97
1.03
0.97
1.03
0.97
1.03
0.97
Sphere cell (Emax =1.045) Rotated ellipsoid cell – short radius
polarization(Emax =1.059)
Rotated ellipsoid cell – long radius
polarization(Emax =1.028)
Cube – parallel polarization
(Emax =1.059)
Cube – diagonal polarization
(Emax =1.063)

11
Conclusion
✓ The E-field concentration ratio 1.063 is
obtained when a cube cell exposed 500GHz
pulse with diagonal polarization.
✓ Lower frequency element included in THz
Gaussian pulse effect much more than
higher element.
✓ A cube cell induces electric concentration
more than a sphere cell against arbitrary pulse
polarization.
✓ E-field in the vicinity of a cell is quantitatively
obtained for the combination of shape and
polarization. Though as a result the effect of
shape and pulse width are clarified, the E-field
concentration is relatively small. More studies
are required for the selective pulse exposure.

12
Acknowledgement
✓About ‘ Bioelectrics ’ Prof. Sunao KATSUKI of Kumamoto Univ. gave
an important suggestion.
✓Dielectric properties in THz are provided by Prof. Yuichi Ogawa .
✓Teppei Misumi, Takuto Muto and Mizuho Yagishita at Science &
Technology Inst., Co. developed the simulation software KeyFDTD
which was used in this study.

13
Thank you for your attention!

Visualization of the Electrical Field in the Vicinity of a THz Pulse Exposed Cell with FDTD Simulation

Recommended

Recommended

More Related Content

What's hot

What's hot (20)

Similar to Visualization of the Electrical Field in the Vicinity of a THz Pulse Exposed Cell with FDTD Simulation

Similar to Visualization of the Electrical Field in the Vicinity of a THz Pulse Exposed Cell with FDTD Simulation (20)

Recently uploaded

Recently uploaded (20)

Visualization of the Electrical Field in the Vicinity of a THz Pulse Exposed Cell with FDTD Simulation