Patent ID: 7519407

Claim:
An implantable medical device comprising: a) an elongated sheath, b) a waveguide disposed within said sheath, c) at least one multi-wavelength light source for illuminating said waveguide, d) at least one multi-wavelength photo-detection means to receive light from said waveguide, e) two or more optical sensors in optical communication with said light source and photo-detection means via said waveguide wherein each sensor is operative to modulate the propagation of light of a different wavelength in said waveguide wherein at least one sensor is for measuring the concentration of oxygenated and deoxygenated hemoglobin by direct contact with blood and comprises: i) a sensor waveguide having a planar support as a cladding on a first surface with a second surface parallel to the plane of the first surface and capable of being exposed directly to a fluid, ii) a reflective surface orthogonal to the direction of propagation of light within the sensor waveguide.