How to mesh thin wires imported from STL files

Hi,

I am trying to import and mesh thin wires (20-30um in diameter) from STL files, but came across the following issues:

1) I can import the STL files, but when messhing, it could have "Self intersections not supported" error.

2) Fractions of the wire would be missing, and create issue when messhing.

3) Is Tetrahetral mesh a good option?

A wire next to it, imported from STL same way could have no issue. (see attached image)

Could you provide some insight into it?

Thanks, Stacey