Pulse Oximetry in the External Auditory Canal
In this paper, we introduce a new sensor technology for measuring plethysmographic parameters, i.e., for pulse oximetry, particularly in mobile people. The sensor uses the auditory canal as a measuring site, plus a novel light path through the tissue of the auditory canal's wall for continuously and reliably measuring arterial oxygen saturation and heart rate under mobile conditions. Measurements with this sensor technology reveal a good ratio in combination with excellent signal quality - ideal prerequisites to make pulse oximetry a continuous unobtrusive mobile monitoring technology. Methods and apparatus for detecting oxygen saturation levels in blood from within an auditory canal of a living being proximal to a tympanic membrane are disclosed. The auditory canal is lined with tissue and includes a proximal bend and a distal bend located between the proximal bend and the tympanic membrane. Oxygen levels are detected by emitting one or more wavelengths of light into a first position on the tissue of the auditory canal in a first region defined by the distal bend and the tympanic membrane. The wavelengths of light are then sensed at a second position on the tissue of the auditory canal in the first region. A blood oxygen saturation level and/or pulse rate is then calculated responsive to intensity information corresponding to the wavelengths of light detected at the second position.