A method for forming a structured polymeric film having a plurality of longitudinally spaced structured on both sides of the structured polymeric film is described. The method includes: providing a rotatable tool having an outer circumferential surface, the outer circumferential surface including a plurality of tool projections; providing a nip roll having a smooth conformable outer circumferential surface opposed to the outer circumferential surface of the tool; introducing a polymer layer into a nip between the tool and the nip roll; pressing the polymer layer between the tool and the nip roll to form web recesses into a first side of the polymer layer and web projections extending away from an opposing second side of the polymer layer, with the tool projections on the circumferential surface of the tool and form a structured web; and removing the structured web from the tool. Sample processing articles are also described.