When measuring core body temperature in a patient, a curved sensor (10) is provide that has a predefined radius of curvature to fit comfortably and closely to a patients forehead. The sensor (10) has at least one releasable securing strip (e.g., Velcro™) that couples the sensor (10) to a headband (14), as well as an adhesive strip (16) that is positioned along one edge of an interior surface of the sensor (10) and couples the sensor (10) to the patients skin. The adhesive strip acts as a hinge that facilitates inspection of the skin beneath the sensor without complete removal of the sensor, and the headband and curvature of the sensor provide a snug fit of the interior surface of the sensor against the patients skin. Additionally, the sensor may be a zero heat flux sensor (34) with a heater (32) placed on one side thereof and a thermister (36) placed on an opposite side thereof, between the heat flux sensor (34) and a patients skin. The heater is adjusted until heat flux through the heat flux sensor is zero, at which point the patients skin surface temperature (as detected by the thermistor) is recorded as a core body temperature. Moreover, the thermister (34, 72) may be quickly calibrated by linearizing a temperature vs. resistance curve therefore, and shifting the linearized curve to a predetermined 15 reference curve.
