Dear Ennio,

Yes, the human body shows impedance for the passage of the current in it. In addition the human body is a signal generator since it generates signals that can be be accessed by probes. There is the cardiac signals, the brain signals, and the muscle activity signals.

The equivalent circuit may be composed of a c-r network. The inductive effect is present but it may be much weaker than the conductive and capacitive effects.

As an example of the equivalent circuit for the skin please see the link: https://pdfs.semanticscholar.org/8e30/f89df45686b99037a4c842d6c7b928c9ceb1.pdf

For the human body equivalent circuit follow the link: http://ieeexplore.ieee.org/document/6180469/

Best wishes

Dear Abdelhalim Zekry, dear Farid Djahli, dear Nikolai Beev,

first of all thank you very much for the answer and for the good information.

I have noted that many documents represent skin, body, cells and tissue as an electronic circuit made up of a parrallel between a capacitor and a resistor with sometimes a resistor in serie with this parallel or a resistor in serie with the capacitor.

It seems that all the models are supposed and then checked by instrument measurement. What I'm investigating and try to understand better is how is possible to represent with an electronic circuit the human body tissue to understand how current with different frequencies interact with biological human tissue and determine the pathways of current flow through the body. Do you know if exist some studies that have already investigated how current at different frequencies interact with the bological human tissue and which are the pathways of the current flow through the body?

Thank you very much!

Best regards

Ennio

Dear Nikolai Beev,

thank you very much for the feedback.

I'm interested to analyze the range between 10kHz to 10MHz.

Do you have any advices?

Best regards

Ennio

Dear Ennio,

How many electrodes you will use to measure the hymen body impedance?

Which part of the body you want to access by your electrodes?

If you use two electrodes attached to the skin and between them human tissues. Then your equivalent circuit must be at least composed of two parallel r-c circuits representing the electrode, then you have two skin equivalent circuits one from every side and then an rc circuit respiring the tissues. Then you can use the vector impedance as a function of frequency to resolve the different parts of body. The human body is partly conductive and partly capacitive and therefore, the complicated equivalent circuit can be reduced int simple R-C circuit as you mentioned above.

One important thing is to fix the objectives of the study.

You can your self propose an equivalent circuit based on the equivalent circuits of the different type of the tissues.

Best wishes

Dear Abdelhalim Zekry,

thank you very much for the feedback.

My aim is to understand better the pathway of the current flow inside the biological tissue. If we vary the frequency of an alternate current from 10 kHz to 10 MHz how will change the pathway of the current flow?

We could answer to this question using this R-C equivalent circuit or maybe with a more complex circuit. Is this the best way to understand the pathway of the current flow inside the biological tissue?

Let me know!

Best regards

Ennio

There are two types of modelling, the behavioral model where one is interested to model the behavior of the physical object with out referring to its physical structure. The other type of modelling is the physically based model where the electrical model is based on the physical structure of the object. I believe the latter one is which you intend. Therefore in my previews comment, i proposed to build your electrics model on the physical based models of the different tissues in the intended path. In this way you can see better how would be the effective part in the different frequencies using the impedance spectroscopy.

Best wishes

Dear Abdelhalim Zekry, dear Nikolai Beev,

thank you very much for the feedback and for the information.

If I have understood well it is difficult to create a good model, because there are too many variable parameters connected to the propreties of the human body like somatotype and so on. In your opinion, could be good for my analisys to check the work of C. Gabriel about the dieletric proprieties of the biological tissue in the range from 10Hz to 10GHz?

Let me know!

Thank you very much for the support

Best regards

Ennio

The human body has many tissue types. You can find the dielectric properties of those tissues here: http://niremf.ifac.cnr.it/tissprop/

I believe that it might be possible to represent *portions* of the human body as equivalent circuits, if you know that the currents are restricted to those portions.

Note that the conductance (resistivity) of human muscle and fat tissue is fairly flat over a wide range of frequencies (but different, since muscle holds much more water content), so the R part of RLC is pretty much constant, but depends on the proportion of muscle or fat. L is probably not a player at all, since the magnetic permeability for human tissue is essentially mu_0. The relative dielectric constant of muscle and fat can vary by many orders of magnitude vs frequency, so C can change a lot, however. Hope this helps.

Dear James Heagy, thank you very much for the answer!

Have a nice day!