| abstract |
An apparatus includes a flexible electrically-insulating substrate including an inner surface and an outer surface. The substrate is shaped to define multiple channels passing between the inner surface and the outer surface, at least some of the channels being concave channels. The apparatus further includes an outer layer of an electrically-conducting metal covering at least part of the outer surface, an inner layer of the electrically-conducting metal covering at least part of the inner surface, and respective columns of the electrically-conducting metal that fill the channels such as to connect the outer layer to the inner layer. |