Abstract: Tunneling and implantation tools that may be used to implant a sensor within a living animal. For example, the sensor may be implanted in subcutaneous tissue below the skin. The sensor may be disk-shaped and may be capable of being compressed (e.g., wrapped) in a more cylindrical shape. The sensor may or may not be able expand on its own (i.e., to force tissue apart to accommodate the sensor in its full disk-shape) after insertion into the living animal. The tunneling tool may have a flat and wide tip, a vibration device, arms attached to a rod at its tip, a spring in a hollow tube at the end of a rod, and/or oscillating teeth. The implantation tool may have jaws that clamp and then release the sensor and/or rods that insert into channels of the sensor and spread apart to assist in opening up a compressed sensor.