The disclosure provides a sensor including a sensor having an external surface and a cannula. The cannula comprises a substantially cylindrical wall encircling a lumen, at least one aperture and a distal end. The sensor is positioned within the lumen and the distal end of the cannula extends beyond the sensor. This configuration functions for example to stabilize chemical reactions associated with the sensor by creating a buffer zone between the sensor and the surrounding tissues at the site of implantation. In certain embodiments, the sensor can further comprise an accessory material in proximity to the external surface, wherein the accessory material modifies the biological response of a tissue that is in contact with the sensor. The sensor can also comprise anchors that keeps the sensor in contact with subcutaneous tissue of a subject upon insertion of the sensor into the body of the subject.