Electronics are typically manufactured as two-dimensional panels. Yes, you can make flex circuits that curve back around on themselves, but those are really just two-dimensional circuits folded into a third.
Researchers at the University of Houston and the University of Colorado Boulder have found a way to challenge that paradigm and can now create 3D curvy electronics, or circuits printed on a sphere.
The process of putting electronics on a 3D structure involves conformal additive stamp (CAS) printing, a close relative of pad printing, or the printing technology that puts logos on pens. In this process, a party balloon is covered with a urethane elastomer. This balloon stamp is then used to pick up small electric components and deposit them onto an acrylic hemisphere.
The key demonstration of this technique is a hemispherical solar cell, where the surface of a half sphere was covered in small (0.1mm) solar cells. This technique was extended to a hemispherical photodetector array, providing a 39x39 p-n junction array.
This technique is not limited to just placing small bits of silicon down onto a 3-dimensional substrate. The authors of the paper also investigated the creation of a hemispherical antenna by applying an etched copper pattern using the same method, and found it worked sufficiently well.
In the interests of experimentation, the researchers also investigated applying electronics to substrates that are not regular hemispheres. Wire mesh was applied to the corner of a cylinder, a funnel, a pyramid, and a rock, all painted with a urethane coating.
While the majority of electronics manufacturing will continue in two dimensions, there is an increasing need for electronics that can be applied to arbitrary 3D surfaces. This especially includes optoelectronics such as VR and AR displays, up to and including ‘smart’ contact lenses.