Medical sensor and method for calibration

A medical capsule being equipped with a CPU and a sensor device, the sensor device comprising (i) at least one light emitting element, and (ii) at least one light detecting element, wherein the medical capsule is adapted to detect the presence or non-presence of blood and/or bile containing Biliverdin on the basis of light absorption properties of blood and Biliverdin, wherein the medical capsule further comprises a recess or gap at its outer surface between the at least one light emitting and the at least one light detecting element, wherein:

• the at least one light emitting element emits monochromatic violet light, monochromatic green light, and monochromatic red light, of different wavelength ranges;
• the at least one light detecting element generates a separate sensor signal associated with measured light intensities Iviolet, Igreen and Ired of at least each of the wavelength ranges of the light from the at least one light emitting element;
• and
• the medical capsule differentiates the presence of blood from the presence of bile containing Biliverdin by evaluating a quotient Ired/Igreen of the measured intensity of red light Ired divided by the measured intensity of green light Igreen transmitted to the at least one light detecting element, for which the absorption characteristics of blood are higher than that of Biliverdin,
• the medical capsule being configured to distinguish a quotient Ired/Iviolet of the measured intensity of red light divided by the measured intensity of violet light in a case where bile containing Biliverdin is present from a quotient Ired/Iviolet in a case where blood is present.