I just learned about microfluidics[1] the other day, so now I'm seeing possible applications everywhere. I wonder if this is one such possible application.

[1]https://en.wikipedia.org/wiki/Microfluidics

How about a sphere-ish thing, then?

Or a tube-like cylindrical thing?

You need more surface area not less.

I suppose a long tube might work, but that'd be a weird shape to work with.

the whole idea of a flat linear trace may be a dead end... high frequencies dont propagate very well through the cross sectional area of a conductor...skin effect and antenna effect dictate many of the design constraints regarding width thickness proximity and linear segment length...we may begin to see hollow duct waveguides required to manage propagation of gigahertz even terahertz frequency electron waves if we dont go full out photonic...im hoping to see carbon/ graphene nanotube die production facilities, even if only experimental for the remainder of my lifetime...lets catch the wave and promote to the next level...

Not insurmountable I would gather. Probably just need microscale heat pipes. Then again, I dunno physics well enough to know this won't work.