Aqueous buffer protection system for biosensors

A biosensor system comprising:

• a conduit with an inner lumen with a first end for receiving a target biological fluid and a second end;
• a sensor coupled to the inner lumen remotely from a source of the target biological fluid to detect a target substance;
• and
• a supply unit for a buffer solution coupled to the inner lumen,
• wherein the supply unit includes a mechanism for advancing the buffer solution along the inner lumen so that the target biological fluid can be purged from an area around the sensor, and wherein, when a measurement is desired, the buffer solution is withdrawn into the supply unit so that the target biological fluid enters the inner lumen and contacts the sensor,
• wherein the buffer solution includes a predetermined calibration concentration of the target substance, wherein the predetermined calibration concentration is less than a predetermined range of concentration of the target substance in the target biological fluid,
• wherein a difference between a measurement of the target substance in the buffer solution and the predetermined calibration concentration identifies a correction which is applied to the measurement for the target biological fluid, and
• wherein the measurement of the target substance in the buffer solution identifies an end-of-life of the sensor when the measurement is less than a threshold.