Abstract: The invention herein disclosed provides for devices and methods that can detect and control an individual polymer in a mixture is acted upon by another compound, for example, an enzyme, in a nanopore. Of particular note is the stability of the system in a saline medium and to detect individual nucleotide bases in a polynucleotide in real time and which may be used to sequence DNA for many hours without change of reagents. The invention is of particular use in the fields of forensic biology, molecular biology, structural biology, cell biology, molecular switches, molecular circuits, and molecular computational devices, and the manufacture thereof.