Patent ID: 7499738

Claim:
An assembly for measuring the concentration of an analyte in a biological matrix, comprising: an implantable optical-sensing element, said implantable optical-sensing element comprising: a body wherein said body has a proximal end and a distal end; a membrane mounted on said body, said membrane and body defining a cavity for receiving said analyte, said membrane being substantially permeable to said analyte and substantially impermeable to background species in said biological matrix; and a refractive element disposed in said cavity, wherein the refractive element comprises a plurality of plates sequentially arranged traverse to a longitudinal axis of said body; a source for providing light of a first intensity onto said refractive element in said cavity; a detector for receiving light of a second intensity from said cavity; and a signal-processing and computing element optically coupled to said detector for comparing said first and second intensities, and relating said intensities to analyte concentration.