NOVELTY - Fabricating (M1) a fluidic device (I) involves forming a nanofluidic region on a substrate (II), forming a microfluidic region on (II) and forming a gradient interface region between the nanofluidic region and the microfluidic region.    USE - (M1) is useful for fabricating a fluidic device (claimed).    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for the following:    (1) forming (M2) a microfluidic/nanofluidic device involves forming a nanofluidic region on (II), coating photoresist on (II), providing a blocking mask over the photoresist, where the blocking mask extends over a portion of the photoresist and exposing the blocking mask to light, where the photoresist has a gradient of undeveloped photoresist along a light diffraction region forming a gradient interface region and the light diffraction being caused by an edge of the blocking mask;    (2) (I) formed by (M1) or (M2);    (3) a system (III) for carrying out (M1) comprising units for forming nanofluidic region, microfluidic region on (II) and a unit for forming the gradient interface region;    (4) a fluidic chip (IV) comprising a surface having a nanofluidic region formed in the material of the surface, a microfluidic region on the surface, a gradient interface region between the nanofluidic region and the microfluidic region, a sample reservoir (V) in fluid communication with the microfluidic region, where the sample reservoir is capable of receiving a fluid and a waste reservoir (VI) in fluid communication with the channels, where the waste reservoir is capable of receiving a fluid;    (5) analyzing (M3) a macromolecule, involves providing a surface having a nanofluidic region formed of several channels in the material of the surface, a microfluidic region on the surface, a gradient interface region between the nanofluidic region and the microfluidic region, (V), (VI), providing (V) with a fluid comprising a macromolecule, transporting the macromolecule between the microfluidic region and the nanofluidic region to elongate the macromolecule, detecting a signal transmitted from the elongated macromolecule and correlating the detected signal to a property of the macromolecule; and    (6) a cartridge comprising (IV) and capable of being inserted and removed from a system for carrying out macromolecular analysis, where (IV) comprises a nanochannel array comprising a surface having a nanofluidic region formed in the material of the surface, a microfluidic region on the surface, a gradient interface region between the nanofluidic region and the microfluidic region, (V), (VI) and an apparatus for detecting a signal transmitted from the fluid in the channel.    DESCRIPTION OF DRAWING(S) - The figure shows a graph representing entropy change to the nanochannels of the fluidic device.