An implantable device for body tissue, including an electrical subsystem that flexes within and interfaces with body tissue and a carrier that operates in the following two modes: provides structural support for the electrical subsystem during implantation of the device in body tissue and allows flexing of the electrical subsystem after implantation of the device in body tissue. The implantable device is preferably designed to be implanted into the brain, spinal cord, peripheral nerve, muscle, or any other suitable anatomical location. The implantable device, however, may be alternatively used in any suitable environment and for any suitable reason.