Patent ID: 8821621

Claim:
A filter system comprising: a filter cartridge housing having a removable housing portion; a filter medium disposed within the filter cartridge housing; a optical analyte sensor comprising a detection medium that changes at least one of its optical characteristics in response to an analyte, the optical analyte sensor disposed within the filter cartridge housing and attached to a wall of the filter cartridge housing such that the detection medium is in fluid communication with the filter medium; and an optical reader comprising at least one light source and at least one detector, the optical reader attached to the removable housing portion such that, when the removable housing portion is attached to the filter cartridge housing, at least a portion of light emitted by at least one light source is reflected from the optical analyte sensor and captured by at least one detector, wherein the filter cartridge housing wall comprises a transparent portion to which the optical analyte sensor is attached and through which the optical analyte sensor is optically interrogatable by the optical reader, and wherein the filter cartridge housing wall to which the optical analyte sensor is attached is not a wall of the removable housing portion of the filter cartridge housing.