Percutaneous skin access devices include a plurality of locked connecting units mounted to the exterior surface of an implantable medical object which, in position, is configured to penetrate the skin of a subject. The biomedical return electrode comprises an electrode conductor for receiving electrical energy from tissue via a return path, and a thermochromic liquid crystal layer coupled to the conductor. The beam propagating from the sample is separated into two parts, with one part having a polarization direction different than the polarization direction of the other beam part. Such an apparatus may further include direction control or zoom control objects as interactive overlays on the displayed map image, and may also include route or location overlays on the map image.