An apparatus can include a subassembly having one or more electrode elements, each electrode element having a skin-facing side and a skin-facing surface. The apparatus can further comprise a skin contact layer comprising a conductive adhesive. The skin contact layer can be coupled to the subassembly and can be disposed on the skin-facing side of the electrode elements. The conductive adhesive is electrically coupled to the electrode and configured to contact skin of a subject. At least a portion of the skin contact layer is selectively removable from the subassembly.