Table 1

Electrical and geometric parameters in the model
Electrical properties Source Thickness (mm) Source
Location (sole/rest of foot)
Tissue Heel Arch Forefoot
Bone ϵr 10,000 [23] Sole & rest 10 10 10
marrow σ (S/m) 0.09
Cortical ϵr 3,000 [23] Sole & rest 6 6 6 [15]
bone σ (S/m) 0.02
Muscle ϵr 1.5×106 [24] Rest 3 3 3 [25]
σ (S/m) 0.5 Sole 0 2 0 US *
Fat ϵr 10,000 [24] Rest 4 4 4 [16]
σ (S/m) 0.025 Sole 9.7 5.3 6.1 US
Dermis ϵrr 1.26×106 [22] Rest 1.3 1.3 1.3 [16]
ϵrz 4.01×105
σ (S/m) - r 2.57 Sole 5.1 4.3 4.6 US-SB **
σ (S/m) - z 1.62
Vital ϵr - r 2.71×105 [22] Rest 0.042 0.042 0.042 SB
epidermis ϵr - z 7.30×104
σ (S/m) - r 0.95 Sole 0.213 0.094 0.107 SB
σ (S/m) - z 0.15
Stratum ϵr 1,500 [21] Rest 0.033 0.033 0.033 SB
corneum σ (S/m) 5×10-4 Sole 0.748 0.161 0.253 SB

The relative permittivity (ϵr) and conductivity (σ) were adopted from literature. The geometry values for the sole of the foot were determined from ultrasound (US) scans and the skin biopsies (SB) used for the Nav1.7 immunochemistry. Since the US scans provided only a bulk measure for the entire skin, and the SB provided only an estimate of the thickness of the stratum corneum and vital epidermis (*), the thickness of the dermis was calculated as the thickness of the entire skin subtracted the thickness of the entire epidermis (**, Stratum corneum + Vital epidermis).

Frahm et al.

Frahm et al. BMC Neuroscience 2013 14:116   doi:10.1186/1471-2202-14-116

Open Data