A physiological monitor is provided for determining a physiological parameter of a medical patient with a multi-stage sensor assembly. The monitor includes a signal processor configured to receive a signal indicative of a physiological parameter of a medical patient from a multi-stage sensor assembly. The multi-stage sensor assembly is configured to be attached to the physiological monitor and the medical patient. The monitor of certain embodiments also includes an information element query module configured to obtain calibration information from an information element provided in a plurality of stages of the multi-stage sensor assembly. In some embodiments, the signal processor is configured to determine the physiological parameter of the medical patient based upon said signal and said calibration information.