Evaluating sim4life for tDCS

Hello, I'm evaluating sim4life, for that I'm using a spherical model of the head and the application of tDCS. I am using COMSOL as a reference. At Comsol, there is flexibility (to me) regarding the application of current or voltage. At sim4life it seems that it is necessary to change the scale using the current density. However, performing these simulations or operations in sim4life is still a little difficult (perhaps due to the use of another interface...).

Is the approach, as shown in images, correct?
Can I use expressions in a similar way as in Comsol?
For example, in Comsol, to calculate the average area of a given surface (interface between two tissues) that intersects with a cylinder, just use the surface integration tool (expression (x * x + y * y) <= 0.03 ^ 2 && z> = 0 ). How to do this in sim4life?

Below are some images, any help is welcome!



Captura de tela 2021-02-04 094131.png

Captura de tela 2021-02-04 094848.png

Captura de tela 2021-02-04 094023.png

Captura de tela 2021-02-04 094600.png

Captura de tela 2021-02-04 094331.png

Captura de tela 2021-02-04 094253.png