  High-fidelity analysis of translocating biomolecules through nanopores
demands shortening the nanocapillary length to a minimal value. Existing
nanopores and capillaries, however, inherit a finite length from the parent
membranes. Here, we form nanocapillaries of zero depth by dissolving two
superimposed and crossing metallic nanorods, thereby opening two overlapping
nanofluidic channels molded in a polymeric resin. In an electrolyte, the
interface shared by the crossing fluidic channels is mathematically of zero
thickness and defines the narrowest constriction in the stream of ions through
the nanopore device. This novel architecture provides the possibility to design
nanopore fluidic channels, particularly with a robust 3D architecture
maintaining the ultimate zero thickness geometry independently of the thickness
of the fluidic channels. With orders of magnitude reduced biomolecule
translocation speed, and lowered electronic and ionic noise compared to
nanopores in 2D materials, our findings establish interfacial nanopores as a
scalable platform for realizing nanofluidic systems, capable of single-molecule
detection.
