A sensing decal (400) for use in the production of a sensor, includes a flexible release layer (401), a conductive ink layer (402) and an adhesive layer (403). The conductive ink layer is printed onto a first surface (404) of the flexible release layer and the adhesive layer is printed onto the conductive ink layer. The first surface includes a substantially non-uniform surface (405) and the conductive ink layer includes at least one patterned element (503-509) providing a predetermined set of electrical properties for formation of a sensor.