Described embodiments include an apparatus, including an intrabody probe configured for insertion into a body of a subject, and at least one electrode unit coupled to a distal portion of the probe. The electrode unit includes a flexible electrically-insulative substrate, comprising an outer surface and an inner surface, and one or more pairs of electrically-conductive coatings that coat the outer surface and are configured to sense electrophysiological signals from tissue within the body of the subject, each of the pairs including an inner coating and an outer coating that surrounds the inner coating without contacting the inner coating. The electrode unit further includes respective traces that coat the inner surface and are configured to carry the signals sensed by the electrically-conductive coatings, and multiple electrically-conductive vias that pass through the substrate and connect the traces to the electrically-conductive coatings, respectively. Other embodiments are also described.
