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Dielectrical properties of living epidermis and dermis in the frequency range from 1 kHz to 1 MHz

B. Tsai
B. Tsai
, 
H. Xue
H. Xue
, 
E. Birgersson
E. Birgersson
, 
S. Ollmar
S. Ollmar
 and 
U. Birgersson
U. Birgersson
   | Jul 02, 2019
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Published Online: Jul 02, 2019
Page range: 14 - 23
Received: Nov 28, 2018
DOI: https://doi.org/10.2478/joeb-2019-0003
Keywords
© 2019 Tsai, Xue, Birgersson, Olmar, Birgersson, published by Sciendo
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Fig.1

Schematic of (a) the four-electrode EIS probe with a sense (1), guard (2), second inject (3) and first inject (4); (b) the electrodes of the probe and the stripped skin comprising living epidermis and dermis; and (c) the reduced model consisting of dermis with the living epidermis and electrodes reduced to boundary conditions.
Schematic of (a) the four-electrode EIS probe with a sense (1), guard (2), second inject (3) and first inject (4); (b) the electrodes of the probe and the stripped skin comprising living epidermis and dermis; and (c) the reduced model consisting of dermis with the living epidermis and electrodes reduced to boundary conditions.

Fig. 2

The mean (depth 1 ●; depth 5 ■] and standard deviations (error bars) for the (a) magnitude and (b) phase of the experimentally measured impedances. The fitted mean resistivity and relative permittivity and their standard deviations can be found in (c) and (d) respectively for the living epidermis (♦) and dermis (▼); the fitted equations, Eqs. 7-8, are shown as lines. In (e) and (f), the validation set for depth setting 3 is shown for the experiments (●) and model predictions (lines).
The mean (depth 1 ●; depth 5 ■] and standard deviations (error bars) for the (a) magnitude and (b) phase of the experimentally measured impedances. The fitted mean resistivity and relative permittivity and their standard deviations can be found in (c) and (d) respectively for the living epidermis (♦) and dermis (▼); the fitted equations, Eqs. 7-8, are shown as lines. In (e) and (f), the validation set for depth setting 3 is shown for the experiments (●) and model predictions (lines).

Skin thickness (mean value ± standard deviation) at the volar forearm for epidermis, stratum corneum and dermis. Some measurement techniques are: Confocal Microscopy (CM), Confocal laser scanning microscopy (CLSM), Optical coherence tomography (OCT), Transepidermal water loss (TEWL), Confocal Raman spectrometer (CRS) and Ultrasound (US).

ED (μm)SubjAgeMeasurementSource
73.54±2.841023 - 47CM[12]
89±91519 - 24CLSM[13]
71.8±103021 - 35OCT[14]
102±7.4520 - 35OCT[15]
66.39±5.821920 - 29OCT[16]
65.1±8.9831 - 37OCT[17]

Dimensions and material parameters.

Current detection width, w11 mm
Ceramic width, w2, w4, w60.15, 0.15, 1.9 mm
Guard width, w30.3 mm
Secondary inject width, w50.5 mm
Primary inject width, w70.5 mm
Living epidermis thickness, hLE61 μm
Dermis thickness, hDE1.0 mm
Inject voltage, V00.05 V
Depth setting, α0.1, 0.58, 1
Electrical permittivity in vacuum,8.85 x10-12 Fm-1
ɛ0 [28]

Coefficients for the conductivity and relative permittivity of the skin layers for 1 kHz to 1 MHz.

jcjLE$\text{c}_{j}^{LE}$djLE$\text{d}_{j}^{LE}$
01.6306×10-2-2.3922×10-2
1-3.3591×10-15.5919×10-1
22.7019×100-5.2033×100
3-1.0667×1012.4090×101
42.0531×101-5.6056×101
5-1.3260×1015.7328×101
jcjDE$\text{c}_{j}^{DE}$djDE$\text{d}_{j}^{DE}$
0-1.0475×10-2-2.5399×10-1
12.2902×10-15.5554×100
2-1.9609×100-4.7903×101
38.2439×1002.0330×102
4-1.7209×101-4.2527×102
51.4687×1013.5741×102
eISSN:
1891-5469
Language:
English
Publication timeframe:
Volume Open
Journal Subjects:
Engineering, Bioengineering and Biomedical Engineering, Biomedical Electronics, Life Sciences, Biophysics, Medicine, Biomedical Engineering, Physics, Spectroscopy and Metrology
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