THE ELECTRIC CAPACITY OF THE HUMAN SKIN

Nicolae-Marius BÂRLEA, Sânziana Iulia BÂRLEA

Tehnical University of Cluj-Napoca,Physics Department, 
Str. C. Daicoviciu 15, ROMANIA,
 E-mail: mbirlea@phys.utcluj.ro 

The body can be considered as a composite volume conductor comprising a number of spatially distributed tissues with differing electrical properties, electrical conduction within biological tissues is due to the movement of ionic charge carriers [1]. The conduction current Ic will develop due to the movement of mobile ions within the aqueous biological medium, related to the tissue's conductivity . The bound charges within tissues give rise to complex dielectric properties, and thus displacement currents Id will contribute to time-varying electrical behaviour. A sinusoidally varying voltage V is applied between the faces of a unit cube of tissue, the resulting current flow Ic and Id will be [2]: 

		Ic = V∙			Id = V∙∙r∙o					(1)

where: 	 is the electrical conductivity (Sm-1),  circular frequency of the sinusoidal voltage, o dielectric permittivity of free space, r the relative permittivity (dimensionless). 
In this study we confirm that biologically active points (BAP) have lower resistance and higher capacitance than the surrounding skin do [3], using time constant measurements (fig).

The experimental arrangement.
REFERENCES
1.	I. Fl. Dumitrescu, Omul şi mediul electric. Fenomene bioelectrice de suprafaţă, Editura ştiinţifică şi enciclopedică, Bucureşti 1976
2.	P.Metherall, Three Dimensional Electrical Impedance Tomography of the Human Thorax, (thesis 1998), http://www.shef.ac.uk/uni/academic/I-M/mpce/rsch/pmeth/thesis.html
3.	D. Constantin, C. Ionescu-Târgovişte (coord.), Acupunctura de la tradiţie la ştiinţele moderne, Editura ştiinţifică şi enciclopedică, Bucureşti 1988