An electrode strip for use in an electrochemical sensor for measuring a compound in a sample, comprising: an elongated electrode support defining a sample transfer path for directional flow of the sample from an application point along said electrode support; a working electrode in said sample transfer path said working electrode comprising an enzyme which catalyzes a reaction involving a substrate for said enzyme or a substrate catalytically reactive with an enzyme and a mediator which transfers electrons between said enzyme-catalyzed reaction and said working electrode to create a current representative of the activity of said enzyme and representative of the compound; a reference or counter electrode in said sample transfer path; and a covering layer defining an enclosed space over the sample transfer path, the reference or counter electrode and said working electrode, said covering layer having an aperture for receiving sample into said enclosed space; said aperture spaced away from and upstream of said electrodes in said sample transfer path and said reference or counter electrode spaced downstream of said working electrode in said sample transfer path. view more

The strip claimed in claim 11 in which said reference or counter electrode is spaced downstream of any portion of said working electrode in said sample transfer path.