There is provided a nanopore disposed in a support structure, with a fluidic connection between a first fluidic reservoir and an inlet to the nanopore and a second fluidic connection between a second fluidic reservoir and an outlet from the nanopore. A first ionic solution of a first buffer concentration is disposed in the first reservoir and a second ionic solution of a second buffer concentration, different than the first concentration, is disposed in the second reservoir, with the nanopore providing the sole path of fluidic communication between the first and second reservoirs. An electrical connection is disposed at a location in the nanopore sensor that develops an electrical signal indicative of electrical potential local to at least one site in the nanopore sensor as an object translocates through the nanopore between the two reservoirs.