Disposable, pre-sterilized, and pre-calibrated, pre-validated sensors are provided. The sensor comprises a disposable fluid conduit or reactor bag and a reusable sensor assembly. An optical bench or inset optical component is integrated within the disposable fluid conduit or bioreactor bag, which provides an optical light path through the conduit or bag. These sensors are designed to store sensor-specific information, such as calibration and production information, in a non-volatile memory chip on the disposable fluid conduit or bag and on the reusable sensor assembly. Methods for calibrating the sensor and for determining a target property of an unknown fluid are also disclosed. The devices, systems and methods relating to the sensor are suitable for and can be outfitted for turbidity sensing.