Fig.1

Fig. 2

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) | Subj | Age | Measurement | Source |
|---|---|---|---|---|
| 73.54±2.84 | 10 | 23 - 47 | CM | [12] |
| 89±9 | 15 | 19 - 24 | CLSM | [13] |
| 71.8±10 | 30 | 21 - 35 | OCT | [14] |
| 102±7.4 | 5 | 20 - 35 | OCT | [15] |
| 66.39±5.82 | 19 | 20 - 29 | OCT | [16] |
| 65.1±8.9 | 8 | 31 - 37 | OCT | [17] |
Dimensions and material parameters_
| Current detection width, w1 | 1 mm |
| Ceramic width, w2, w4, w6 | 0.15, 0.15, 1.9 mm |
| Guard width, w3 | 0.3 mm |
| Secondary inject width, w5 | 0.5 mm |
| Primary inject width, w7 | 0.5 mm |
| Living epidermis thickness, hLE | 61 μm |
| Dermis thickness, hDE | 1.0 mm |
| Inject voltage, V0 | 0.05 V |
| Depth setting, α | 0.1, 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_
| j | ||
| 0 | 1.6306×10-2 | -2.3922×10-2 |
| 1 | -3.3591×10-1 | 5.5919×10-1 |
| 2 | 2.7019×100 | -5.2033×100 |
| 3 | -1.0667×101 | 2.4090×101 |
| 4 | 2.0531×101 | -5.6056×101 |
| 5 | -1.3260×101 | 5.7328×101 |
| j | ||
| 0 | -1.0475×10-2 | -2.5399×10-1 |
| 1 | 2.2902×10-1 | 5.5554×100 |
| 2 | -1.9609×100 | -4.7903×101 |
| 3 | 8.2439×100 | 2.0330×102 |
| 4 | -1.7209×101 | -4.2527×102 |
| 5 | 1.4687×101 | 3.5741×102 |