In some embodiments, an apparatus includes a substantially rigid base and a flexible substrate. The substantially rigid base has a first protrusion and a second protrusion, and is configured to be coupled to an electronic device. The flexible substrate has a first surface and a second surface, and includes an electrical circuit configured to electronically couple the electronic device to at least one of an electrode a battery, or an antenna. The flexible substrate is coupled to the base such that a first portion of the second surface is in contact with the first protrusion. A second portion of the second surface is non-parallel to the first portion.