Abstract: In order to facilitate diffusive transfer of an entity such as a solute between immiscible fluids and subsequent separation of the liquids without mixing, a method and an apparatus are disclosed and have first and second flow paths carrying first and second immiscible fluids on opposite sides of a foraminous sheet. The height of the apertures in the sheet is not greater than 200 micrometers (measured perpendicular to the width of the sheet and to the direction of fluid flow), and a stable interface is formed between the fluids within each aperture with a significant amount of fluid flow immediately adjacent the interface. Diffusive transfer takes place across the interface, and subsequently the fluids flow away from the region without mixing. The width of the flow paths measured perpendicular to sheet lies between 10 and 500 micrometers. The walls of each aperture may be parallel or tapered.

Abstract: A gas sensor including a substrate that is porous at least in a region thereof to permit permeation of gas. At least first and second porous electrodes are formed as planar elements on the substrate. The substrate is bonded to a housing in a peripheral area of the sensor. A portion of the first electrode extends into this peripheral area and is rendered non-porous to prevent the leakage of electrolyte therethrough.