A sensor probe suited for implanting into the skin of a person includes a sensor body which may be formed from a polymer which includes 2-hydroxyethyl methacrylate (HEMA). A sensing system is supported by the body. The sensing system exhibits a detectable change when the probe is exposed to the analyte in the fluid. The sensing system may include an enzyme capable of catalyzing a reaction of the analyte to form a reaction product and a dye system which absorbs in the infrared region of the spectrum in response to the reaction product.