Patent ID: 7909972

Claim:
An electrochemical sensor, comprising: an elongated housing defining a longitudinal axis, the housing having a proximal end and a distal end configured to be exposed to a target fluid, the housing defining an interior configured to hold a gelled or liquid reference electrolyte therein, the housing having an outer member axially aligned with the longitudinal axis of the housing, the outer member including an outer tubular wall substantially impermeable to ionic flow, an inner member formed of material substantially impermeable to ionic flow and disposed within the outer wall, the inner member including an inner tubular wall defining an axial bore axially aligned with the longitudinal axis of the housing, a plurality of cross members formed of material substantially impermeable to ionic flow, each cross member of the plurality of cross members generally ring-shaped circumscribing the inner tubular wall and extending to the outer wall, cooperatively defining the interior of the housing to include a plurality of levels that are generally ring-shaped and axially aligned in spaced relationship to each other, wherein the plurality of levels are filled with the reference electrolyte, and a plurality of apertures defined by the housing, each aperture positioned to connect two adjacent levels of the plurality of levels such that the plurality of apertures enable and require ionic flow in the reference electrolyte to pass through each of the plurality of levels in a sequential manner between a distal level proximate to the distal end of the housing and a proximal level; a measuring electrode disposed in the axial bore and having a tip extending beyond the distal end of the housing to be exposed to a target fluid; a reference electrode submerged in the reference electrolyte within the housing; and a junction plug comprising a porous material, the junction plug is disposed at the distal end of the housing to contact the target fluid.