How do we put electrodes on the skin surface?

[gotou]

As shown in the attached image, the electrodes are flat, resembling a plate, which causes them to float off the body. How can I modify the placement so that the electrodes conform to the surface of the body, as they would in a real-world scenario?

[gc00]

@gotou As far as I know there is not a way to place them automatically, unless they are small cylinders. There is the “project on surface” option that can be useful.
I used to place them manually with the “bend” option, even though is a little bit time consuming.

[halder]

Hi @gotou, I believe you have written to s4l-support, and we are working giving sending you a final project with all the questions you have sent. But regarding this specific question I am adding gifs showing the steps.

(a) Open File then Preferences and ensure within "Modeling " ensure disable triangle mesh model picking option is disabled. Might need to restart Sim4Life in case it is not.

(a) Create the blocks on the xy plane and mesh the solids (remesh the block if necessary)

(b) Use Surface Projection ensure the surface you want to project is selected first followed by the target you want to project onto.

Look into section 2.2.7.8 of the Sim4Life manual. Hope this help, we will get back to you soon with the other answers. Thank you.

[gotou]

@halder
Thank you for your reply.

I read in the Sim4Life manual that a module needs to be purchased for remeshing. Since this option is not available in this image, does this mean that the module has not been purchased yet?

[bryn]

You can achieve the same thing without the remesh tool.

Option 1

• before converting the brick (electrode) into a mesh, set the faceting settings (Mesh Tools -> Faceting) to increase the triangle resolution (e.g. 1-5mm). You cannot bend a single triangle: to approximate a curved surface the mesh needs to be refined somewhat

Option 2

• if you already converted the solid body to a triangle mesh, you can use Mesh Tools -> Subdivide -> choose linear subdivision

[gotou]

@bryn
Thank you for your reply.

I've managed to convert the solid object into a triangle mesh, but I'm having trouble applying the skin surface to it. Could you please guide me on how to proceed from this point?

If possible, would you be able to provide a step-by-step GIF showing how to apply the skin to the mesh surface? I understand you may be busy, but your help would be greatly appreciated.

Thank you very much for your time and assistance.

[bryn]

You don't "apply the skin" to something. The process suggested and described with gifs above is to "project" (Surface Projection) some entities (electrodes) onto some surface (e.g. the Skin).

To activate the tool you need to select the electrodes AND skin (last selected entity) entities.

[bryn]

@gotou here is a video I created some time ago explaining how to project an entity onto the skin. The video creates a 3d text entity, but the same works for a brick.

• create entity in XY plane
• set faceting settings, e.g. edge length 1-5mm (Mesh Tools -> Edit Faceting)
• convert to triangle mesh (Mesh Tools -> To Mesh)
• select entity and Skin
• start projection tool (Project -> Surface Projection)

Youtube Video

[gotou]

@bryn

Thank you for your response .

I followed the steps as shown in the video:

Create the XY entity
Set the facets
Convert to a mesh
Modify the skin as needed using the Mesh Doctor
Select the entity, then select the skin
Perform the projection
However, as shown in the attached image, the result appears to be piercing perpendicularly into the skin.

Do you know why this might be happening?

I look forward to your response

[bryn]

• did you try to move/pre-align the "XY entity" (using Move tool)? If yes, please don't do that.
• can you share the XY entity or run following script and share the output?

import XCoreModeling as xcm

# assumes you select the XY entity, then run the script
xy_entity = xcm.GetActiveModel().SelectedEntities[0]
p1, p2 = xcm.GetBoundingBox([xy_entity])
print(f"p1={p1}, p2={p2}")

[gotou]

＞did you try to move/pre-align the "XY entity" (using Move tool)? If yes, please don't do that.
I was able to properly attach it to the surface by using projection without the move tool.

can you share the XY entity or run following script and share the output?
This was output.

p1=205 179 1799 , p2=205 229 1894

Why doesn't it work correctly when using the move tool?

[bryn]

glad you managed

[gotou]

@bryn
I figured out how to project a single object. However, how can I project a two-layer object onto the skin? The idea is that the first layer is gel, and the second layer is an electrode plate. I tried various methods, but I couldn't figure out how to do it in two layers. I tried projecting the gel onto the skin first and then placing an electrode plate the same size as the gel on top, but the projection was applied to both the front and back of the gel.
(Gel is yellow,electrode is purple)

[bryn]

• the entities (in the XY plane) should be one above the other
• select BOTH entities, and the skin
• project both at the same time (pick position, edit angle, etc.)

[bryn]

with "automatic centering", the object will be partly inside the skin.
if you disable automatic centering, you can project all object above each other (and the skin)

[gotou]

@bryn @gc00 @halder
Thank you so much, You've been very helpful !