Brain tissue

Dielectric constant ${\epsilon }_r$

Conductivity $\sigma$ (S/m)

Cerebrospinal fluid

68

2.5

Eyeball

5.447

0.053

Gray matter

52.282

0.985

Brain parenchyma

42

0.7

White matter

46

0.82

Skull

12

0.2

Skin

40.936

0.089

Blood

61

1.6