A sensor assembly (10) has a substrate (12) with first and second opposite surfaces (14, 16), at least one analyte sensor (18) positioned on the first surface (14), and at least one electrical contact (20) positioned on second surface (16) and in electrical communication with a corresponding one of the at least one analyte sensor (18). The substrate is formed to define a tube (22) having a single linear seam (38), wherein said first surface (14) is the exterior surface (30') and said second surface (16) is the interior surface (28') of the tube, and the at least one analyte sensor (18) is disposed on the exterior surface (30'). The sensor assembly further comprises an outer cannula (52) surrounding the tube (22) to define a fluid receiving annulus (54), wherein the tube (22) has a cap (46') for preventing fluid from entering the interior of the tube.
