Patent ID: 8401602

Claim:
A sensor position indicator having an optical sensor with a sensor-on condition in which the optical sensor is attached to and aligned with a tissue site so as to transmit light into the tissue site and detect the light after attenuation by pulsatile blood flow within the tissue site and a sensor out-of-position condition in which the sensor is unattached to or misaligned with the tissue site, the sensor position indicator comprising: an optical sensor having a plurality of primary emitters and a detector; the primary emitters generating light generally centered around each of a plurality of primary wavelengths; the primary emitters transmitting light into a tissue site in a sensor-on condition; the detector, in the sensor-on condition, outputting a sensor signal responsive to the primary wavelength light after attenuation by pulsatile blood flow within the tissue site; a secondary emitter that generates light generally centered around a secondary wavelength; the secondary emitter transmitted light is at least substantially attenuated by the tissue site; the detector, in the sensor-on condition, is at least substantially blocked by the tissue site from the secondary emitter so that the sensor signal is not responsive to the secondary wavelength light; the detector, in a sensor out-of-position condition, is at least partially exposed to the secondary emitter so that the sensor signal is responsive to the secondary wavelength light; and a processor responsive to the sensor signal so as to calculate a blood-related physiological parameter in the sensor-on condition and so as to indicate the sensor is unattached to or misaligned with the tissue site in the sensor out-of-position condition; wherein the secondary emitter is driven asynchronously relative to the primary emitters.