Discussion Forum

Hi, I am very new to comsol. As depicted in title, my problem is related to calculating capacitance (AC signal condition) between electrodes. Please refer the below figure for clarity.

figure link

The situation I'd like to simulate is as follows:

(1) Apply exciation signal (e.g. 6Vpp, 1MHz sinusoidal) to an electrode. Let's say the electrode marked 1 is set to the exciation electrode.

(2) Detect the capacitvely coupled signal to another electrode. From electrode makred 2, for instance.

(3) All the other electrodes are set to ground.

My question here is: "How can I assign the domain terminals and/or boundary condition for exciation, detection, and grounded electrodes?"

I tried to get some hints from basic comsol tutorials. I found examples of calculating maxwell capacitances (or admittances) under stationary and frequency domain with 2-electrode parallel plate capacitor. In those situations, assigning the terminals looks quite straightforward since there are only two. And it seems that specifying the capacitance 'between the top & bottom electrodes' are not clearly stated during evalutaion procedure and just trated as global parameter (I'm not sure this is correct).

So I am still confused how I can set appropriate domain/boundary physics in my case. I think the exciation terminal should be set as 'terminal'. Then what about the detection & ground electrodes? All 0V terminals for detection & ground electrodes? or boundary conditions for ground electrodes?

Under a appropriate conditioning, how I can evaluate the local capacitance between excitation - detection electrodes is also ambiguous.

Any advice or comments would be greatly appreciated.

Thanks!

SJ