Method for sensor calibration

An in-vitro diagnostic (IVD) analyzer comprising at least one sensor located in a flow-through sensor path of a detecting unit involving a reaction with oxygen in a sample in order to determine a sample parameter and requiring at least one oxygenated calibration fluid with a certain level of oxygenation for calibration, the IVD analyzer further comprising a fluid-supply unit comprising at least one deoxygenated calibration fluid, a fluid-selection valve comprising one or more fluid input ports for selecting at least one fluid at a time, a common outlet port fluidically connected or connectable via a fluidic line to the sensor path, wherein the IVD analyzer further comprises at least one oxygenation tubing having two ends connected to the fluid-selection valve as a loop, wherein the oxygenation tubing comprises oxygen-permeable walls, and wherein the IVD analyzer further comprises a pump and a controller configured to control the pump and the fluid-selection valve for transporting deoxygenated calibration fluid from the fluid-supply unit into the oxygenation tubing, to wait a predetermined time required for oxygenation of the deoxygenated calibration fluid via oxygen uptake from ambient air through the tubing walls until the required level of oxygenation is obtained, and to transport the thereby obtained oxygenated calibration fluid into the sensor path for calibration of the at least one sensor.