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Hello everybody,

I have designed a volume conductor model which should constitute the spinal cord in a simple fashion. I want to run my tests in the electric current (Comsol 4.0) mode to calculate the electrical field distribution along the spine due to epidural stimulation.

The model consists of 7 different compartments oriented in a cylindrical shape. In the middle between two compartments the electronic array is located. It consists of a thin structure, an isolated material, Paralyne C embedding the the main parts the platinum pads (also in a circular manner).

I am confused now with the boundary conditions especially with the new version 4.0. Electric insulation, initial values and current conservation are set in a default mode. However I can not adjust them. What is the purpose of them? How do they interact with my own BC?

So I tried to set my boundary conditions on my own,
I have set the
1. outer surface to electric insulation (outermost cylinder)
2. electric potential to 2 platinum pads (1 pad = 5.5V, 2 pad = 0V)
3. current conservation between the different compartments.

The simulation gives me no error messages, however something is really wrong, as no reasonable result will be displayed.

Does anybody have an idea how to set the boundary conditions? (also concerning to the already defined BC in the default mode)

Thanks for your time and consideration,

Severin