The present disclosure generally relates to a medical sensor configured to attach to a patient's finger. According to embodiments, a sensor body is attached to a ring such that the sensor body is limited to contact with the patient's finger. The ring may have a fixed diameter or be adjustable. The ring may also include an indicator that facilitates the determination of whether the ring applies appropriate tension to the patient's finger. The sensor body may comprise a strip attached to the ring at two points or a hood that covers the distal end of the patient's finger. The sensor body may be coupled to the patient's finger with adhesives or securing flaps.