A sensor system including a holder with at least one semi-permeable layer that forms a chamber, at least one reactant that reacts with at least one analyte, the at least one reactant being contained within the chamber, and a detector disposed proximate the at least one semi-permeable layer and configured to detect and measure a concentration of a reaction product from reaction of the at least one reactant with the at least one analyte. The at least one semi-permeable layer allows passage of the analyte into the chamber and allows passage of the reaction product to the detector. In a preferred embodiment, the analyte includes glucose, and the reaction product detected includes carbon dioxide.