Open Access

Electrical field landscape of two electroceuticals

O. Wahlsten
O. Wahlsten
, 
J. B. Skiba
J. B. Skiba
, 
I. R. S. Makin
I. R. S. Makin
 and 
S. P. Apell
S. P. Apell
   | May 27, 2016
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Article Category: Articles
Published Online: May 27, 2016
Page range: 13 - 19
Received: Feb 17, 2016
DOI: https://doi.org/10.5617/jeb.2693
Keywords
© 2016 O. Wahlsten, J. B. Skiba, I. R. S. Makin, S. P. Apell, published by Sciendo
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Fig.1

(top) Close-up of a Procellera® dressing. Large dots are Ag and the small dots are Zn. (bottom) A POSiFECT® dressing. For further information we refer to references [25, 27, 28]. Both scales are in centimeters.
(top) Close-up of a Procellera® dressing. Large dots are Ag and the small dots are Zn. (bottom) A POSiFECT® dressing. For further information we refer to references [25, 27, 28]. Both scales are in centimeters.

Fig.2

(top) Equipotential lines (the colors represent electrical potential according to the scale to the right) and corresponding electric field vectors for a representative cross-section through a Procellera® dressing model in the form of rings of alternating metals with length scales in accordance with the real dressing. Ag dots at potential +0.2 V is twice the width of the Zn dots at the potential -0.6 V. They are separated a distance which is slightly larger than the Zn width. The metal rings are sitting on epidermis and have air on top. Notice the strong crowding of equipotential lines between Ag-Zn corresponding to a large electric field of the order of 1 kV/m as is detailed in the bottom figure, for clarity. (bottom) Detailed electric field plot. Notice as we move between Zn and Ag dots the field is of the order of 1 kV/m (solid blue). In the perpendicular direction it peaks at around 400 V/m and drops off into air and epidermis (dashed red). The blue line starts at x=1 mm and ends at 4 mm. In the same way the red one starts at y=1 mm, ends at 4 mm in the direction perpendicular to the dressing and passes directly in the middle of the two dots.
(top) Equipotential lines (the colors represent electrical potential according to the scale to the right) and corresponding electric field vectors for a representative cross-section through a Procellera® dressing model in the form of rings of alternating metals with length scales in accordance with the real dressing. Ag dots at potential +0.2 V is twice the width of the Zn dots at the potential -0.6 V. They are separated a distance which is slightly larger than the Zn width. The metal rings are sitting on epidermis and have air on top. Notice the strong crowding of equipotential lines between Ag-Zn corresponding to a large electric field of the order of 1 kV/m as is detailed in the bottom figure, for clarity. (bottom) Detailed electric field plot. Notice as we move between Zn and Ag dots the field is of the order of 1 kV/m (solid blue). In the perpendicular direction it peaks at around 400 V/m and drops off into air and epidermis (dashed red). The blue line starts at x=1 mm and ends at 4 mm. In the same way the red one starts at y=1 mm, ends at 4 mm in the direction perpendicular to the dressing and passes directly in the middle of the two dots.

Fig.3

(top) Equipotential lines (the colors represent electrical potential according to the scale to the right) and corresponding electric field vectors for a representative cross-section through a POSiFECT® dressing model in the form of a central cathode (held at -1.5 V) in the middle and an anode electrode (ring held at +1.5 V). The electrodes are sitting on epidermis and have air on top. (bottom) Detailed electric field plot. Notice as we move between the electrodes the field is of the order of 1 kV/m (solid blue) in the plane and vanishingly small out of the plane (dashed red). Since electrode distance is larger than width of electrode the field decays quickly away on a length-scale of the order of the size of the electrode.
(top) Equipotential lines (the colors represent electrical potential according to the scale to the right) and corresponding electric field vectors for a representative cross-section through a POSiFECT® dressing model in the form of a central cathode (held at -1.5 V) in the middle and an anode electrode (ring held at +1.5 V). The electrodes are sitting on epidermis and have air on top. (bottom) Detailed electric field plot. Notice as we move between the electrodes the field is of the order of 1 kV/m (solid blue) in the plane and vanishingly small out of the plane (dashed red). Since electrode distance is larger than width of electrode the field decays quickly away on a length-scale of the order of the size of the electrode.

Fig.4

Calculated electrical field around a wound (W) without any wound dressing present [17]. We see a cross-section along the radius of a circular representation of the wound. Notice how the electric field is directed towards the wound in its lower part. At the top of the wound it points in the other direction. The colors represent the electric potential according to the scale to the right, in units of the trans-epithelial potential which exists over the extent of the epidermis. Typically the red color is around 40 mV negative. There is a vanishingly small penetration of the field into dermis and hypodermis (not shown) owing to their large dielectric permittivities. The field strength in the epidermis is typically of the order of 10 V/m. Notice that the extension of the region which is influenced by creating a wound is of the order of millimeters.
Calculated electrical field around a wound (W) without any wound dressing present [17]. We see a cross-section along the radius of a circular representation of the wound. Notice how the electric field is directed towards the wound in its lower part. At the top of the wound it points in the other direction. The colors represent the electric potential according to the scale to the right, in units of the trans-epithelial potential which exists over the extent of the epidermis. Typically the red color is around 40 mV negative. There is a vanishingly small penetration of the field into dermis and hypodermis (not shown) owing to their large dielectric permittivities. The field strength in the epidermis is typically of the order of 10 V/m. Notice that the extension of the region which is influenced by creating a wound is of the order of millimeters.

Fig.5

The electric field in the wound area with a wound dressing Procellera® applied with Ag/Zn closest to the wound edge (top/bottom). The reddish dots are Ag and the blue ones represent Zn. The potential difference between the dots gives rise to an electric field strength that is much larger than that from the body's own field. Notice that when Zn is closest to the wound edge (bottom) there are large electric fields set up with large potential for influencing what happens on a microscopic scale when it comes to cell migration cued by the electric field. Notice that the electric field is not shown in the plane between the dots since it is too large.
The electric field in the wound area with a wound dressing Procellera® applied with Ag/Zn closest to the wound edge (top/bottom). The reddish dots are Ag and the blue ones represent Zn. The potential difference between the dots gives rise to an electric field strength that is much larger than that from the body's own field. Notice that when Zn is closest to the wound edge (bottom) there are large electric fields set up with large potential for influencing what happens on a microscopic scale when it comes to cell migration cued by the electric field. Notice that the electric field is not shown in the plane between the dots since it is too large.

Fig.6

The electric current density in the wound area with a Procellera® wound dressing applied with Zn closest to the wound edge. The current density approaches 1 A/cm2 in the region between the dots (solid blue) and falls off quickly in the perpendicular direction (dashed red). Especially when going down into the dermis, which has a low conductivity compared to the wound fluid.
The electric current density in the wound area with a Procellera® wound dressing applied with Zn closest to the wound edge. The current density approaches 1 A/cm2 in the region between the dots (solid blue) and falls off quickly in the perpendicular direction (dashed red). Especially when going down into the dermis, which has a low conductivity compared to the wound fluid.

Fig.7

The electric field in the wound area with a wound dressing POSiFECT® applied. Of interest is of course the influence of the electrode closest to the wound edge where we see major effects. We therefore only show the situation for the anode ring. Field strengths are much larger than the endogenous electric field also for this electroceutical.
The electric field in the wound area with a wound dressing POSiFECT® applied. Of interest is of course the influence of the electrode closest to the wound edge where we see major effects. We therefore only show the situation for the anode ring. Field strengths are much larger than the endogenous electric field also for this electroceutical.

Summary of modeling parameters used in different regions of figure 4. εr is the relative dielectric permittivity and σ is the electrical conductivity.

AreaThickness (mm)εrσ (S/m)
Wound (W)2.0804.8
Stratum Corneum (SC)0.051044·10-3
Epidermis (E)1.01060.22
Dermis (D)2.01080.22
Hypodermis (H)3.01070.08
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Engineering, Bioengineering and Biomedical Engineering, Biomedical Electronics, Life Sciences, Biophysics, Medicine, Biomedical Engineering, Physics, Spectroscopy and Metrology
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