Patent ID: 6952603

Claim:
An assembly for measuring the concentration of an analyte in a biological matrix, comprising: an implantable optical-sensing element comprising a body; a first semi-permeable membrane mounted on said body, said first semi-permeable membrane being permeable to said analyte, and impermeable to background species in said biological matrix, said first membrane and said body aligned to define a first cavity; a first refractive element disposed in said first cavity; a second membrane mounted on said body remote from said first membrane, said second membrane and said body aligned to define a second cavity; and a second refractive element disposed in said second cavity; a source for providing light into each of said first and second cavities toward said respective first and second refractive elements; a detector for receiving light from each of said first and second cavities; and a signal-processing and computing element optically coupled to said detector for relating said received light to a concentration of said analyte.