E-Field across MEAT
Following my post, I read your source material closer to then ammend
my statements, interleaved below:
On Fri, 05 Sep 2008 12:27:57 -0700, Richard Clark
wrote:
On Fri, 05 Sep 2008 15:11:20 -0400, Jon Mcleod
wrote:
I need to research it, but I should be able to calculate the voltage
required to generate the 1v/cm field in the steak if I know the
dielectric constant of the "meat"...
Hi Jon,
The dielectric constant of anything is a sidebar, or distraction,
simply because you don't know the dc of the original work's cells
either. In all probability they are the same, but this is unnecessary
information.
In fact, they do report the dielectric constant, and as I speculated,
nearly identical to that of steak (or seawater for that matter).
More to the matter is where you derive 1V/cm from the original work's
application of an average of 550V (nearly 3 orders greater) to 1mm gap
(exactly 1 order smaller). Your 1V is off by nearly 4 orders of
magnitude.
In fact, they do report 1V/cm.
The electric field intensity was mapped within the cell, based on
the amplitude (1 V/cm), frequency (100 kHz) and waveform (sine) of
the electric field applied to the cell culture.
Unfortunately their reference for this was
11. Volakis JL, Chatterjee A, Kempel LC. Finite element method
electromagnetics: antennas, microwave circuits, and scattering
applications.
which cannot be applied to a situation where the wavelength of
excitation is 3000 meters and the gap is one thousandth meter. The
calculation of 1V/cm based upon the application of an average of 550V
across a 1mm gap flies in the face of credulity.
However, and again confounding their use of power amplifier to deliver
1 V/cm in the near field, there is the report:
The electric field intensity in the culture medium was measured by
means of a probe, consisting of two (0.25 mm in diameter)
insulated wires with exposed tips 0.5 mm apart, that was dipped in
the culture medium. The wires were connected to a high-input
impedance differential amplifier that translated the waveform
amplitude into a calibrated steady voltage that was digitally
recorded. Field intensities throughout the manuscript are
expressed in peak voltage amplitude per centimeter (V/cm).
Care was taken to eliminate any pickup from the field outside the
culture medium. Continuous field monitoring could also be made by
measuring the potential drop across a 100 Ohm resistor placed in
series with one of the field generating wires.
This last statement lacks data about what voltage was observed and
says nothing of the contribution of field's interaction with the leads
going to it to measure the voltage across them.
I can understand your desire to simply shove your function generator's
output directly into a steak. It is a choice that is tantilizingly
teased as an option given this report of 1 V/cm. It also raises the
curious aversion of the authors from performing the same test and
removing the absurd complexity of amplifiers and remote senors.
Afterall, 1 V/cm is trivial to obtain, demands no external
amplification, and whose level can be monitored from the function
generator itself.
All of this (in concert with missing data and no computation shown)
suggests a problematic correlation of results (which are inarguable)
to field strength.
Again, science would say replicate the conditions and observe if the
results follow. You can make your own correlations. All things being
practical, the application of an average of 550V across a 1mm gap
demands a better reporting of a finding of 1 V/cm in the sample.
73's
Richard Clark, KB7QHC
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