Abstract: Described herein are method and apparatuses (devices and systems) for determining tissue wetness, and particularly lung wetness. In particular, described herein are apparatuses including patch sensors having a plurality of electrodes one a substrate that includes alignment tabs for aiding in alignment. Also described herein are patch sensors having one or more substrate modifications to enhance local flexibility of the patch. Finally, described herein are apparatuses for determining lung wetness that determine the contour of the body region onto which the patch is applied, e.g., using a diagnostic tool to measure body contour.