A sensor which can be implanted in a body part to collect data relating to the body part, the sensor includes a jacket which has a side wall which can be deformed inwardly, and first and second ends. A sensor part is contained within the jacket, and fastened to the jacket at or towards the first end of the jacket. The sensor part is at least partially isolated from compressive forces applied to the sensor which cause the side wall of the jacket to deform inwardly.