Systems, devices, kits, and methods are provided herein in the form of example embodiments that relate to calibration of medical devices. The medical devices can be sensors adapted to sense a biochemical attribute. The embodiments can be used to determine calibration information specific to an individual medical device. The embodiments can determine the calibration information by reference to one or more parameters obtained during manufacturing of the medical device. The embodiments can also determine the calibration information by reference to in vitro testing of the medical devices. The embodiments also apply to systems incorporating those medical devices in their use in the field. Also described are embodiments of modifications to surfaces of sensor substrates, such as through applied radiation and/or the creation of a well, to aid in the placement and/or sizing of a sensor element on the substrate.