Provided is a device comprising a channel through and defined by a plurality of layers surrounding the channel, the channel connecting a first and a second chambers separated by the plurality of layers, wherein the plurality of layers comprise a first layer, a second layer; and a conductive middle layer disposed between the first and second layers, wherein the channel comprises (a) a first region defined by the first layer, denoted as an inlet, that is about 0.5 nm to about 100 nm in diameter and (b) a second region defined by the second layer, denoted as an outlet, wherein the inlet and the outlet are about 10 nm to about 1000 nm apart from each other, and wherein the first and second chambers and the middle layer are connected to a power supply. Also provided are methods of preparing and using the device, in particular for nucleic acid sequencing.