Inquiry About Boolean Operation Issue with the Duke Human Model in Sim4Life

[TaoLiu]

Hey everyone, I’m running into an issue while using Sim4Life and would really appreciate some help.

I’m trying to accurately set up non-invasive surface electrodes for electrical stimulation on a human body model. However, when I use the Duke human model, I found that I can’t use the Boolean module to remove overlapping parts between the electrodes and the body.

Once I select the full DUKE model, the Boolean option disappears from the top operation bar.

Does anyone know how to fix this or what the correct workflow is for applying surface electrodes in this case?

[bryn]

The ViP models are mostly distributed as "posable" models, i.e., you can change the posture using the poser tool. To prevent breaking this feature, "posable" models are marked as non-editable (you probably see the "lock" symbols). To get an editable copy of the Duke model, select the "Bone Mesh System" entity or the containing folder and run "Clone As Static" in the context menu. This will create a static (non-posable) but editable copy.

Note: if you are using a rectilinear grid simulation, you may not need to subtract the electrode from the body. The trick is to assign a higher priority in the voxeler settings to the electrode. This tells the voxeler to voxel the electrodes after the Duke model, effectively overwriting the tissue voxels with electrode voxels. By default if you drag the entities on the simulation, they are assigned a priority 0. Create an extra voxeler settings (Automatic is fine) and assign the priority 1 (or something larger than 0). Then drag the electrode(s) to these voxeler settings. Effectively, this allows you to do complex booleans "for free".

[bryn]

This video shows one possible workflow. The clone as static is a bit quick, but is shows how you could even crop a whole part of the body:
Youtube Video

[TaoLiu]

Thank you very much for your detailed and helpful reply.

Following your suggestion, I tried setting the electrode priority to 1 and the DUKE model priority to 0, and I also defined the electrode material as PEC to perform the electrical stimulation simulation.

However, I noticed that in the simulation results, there is no electric field distribution at the interface where the electrode overlaps with the skin, which seems physically incorrect.

Could you please let me know whether there might be an issue with my setup or if there is a specific modeling step required to correctly represent the electrode–skin contact region?

Thank you again for your time and assistance. I greatly appreciate your support.