MR-Based Implantable Dissolved Oxygen Sensor

A sensor is provided for measuring a dissolved oxygen concentration in vivo when implanted at a tissue site and in ex vivo applications. The sensor includes an article comprising a sensing medium retained within the implantable article by an oxygen-permeable material. The sensing medium comprises an MR contrast agent for oxygen. The sensor is configured to indicate the dissolved oxygen concentration of a fluid, e.g., in vivo at the tissue site, when subjected to an MR-based method.