A method for measuring oxygen saturation of a user, the method includes illuminating a sternal angle of the user by electromagnetic radiation and sensing, by an oxygen saturation sensor included in a device that is removably attached to a user, radiation emitted from the sternal angle of the user as a result of the illuminating, wherein the sensing occurs while the oxygen saturation sensor faces the sternal angle of the user and generating detection signals by the oxygen saturation sensor in response to the sensing of the radiation, wherein the detection signals are indicative of an oxygen saturation characteristic of the user.
