layer in order to help exclude as many interferents from the working area of the electrodes as possible it is often advantageous to employ various microfiltration schemes to exclude red cells and other interferents this may be done by a variety of means the electrodes themselves may be designed to be microporous as is taught by u s pat no 6 231 920 alternatively or in combination the electrode assembly may be covered with a microporous electrically inert material designed to admit sample while excluding as many interferents as possible such layers may be composed of previously synthesized filter materials or built up de nouveaux on the test strip by means of self self assembling chemical compositions such as the mixed hydrophobic hydrophilic particle techniques taught by u s pat nos 5 708 247 and 5 951 836 methods to construct suitable microporus layers were previously discussed in parent application ser no 10 264 206 paragraphs 80 82 the contents of which are incorporated herein by reference as previously discussed it is often advantageous to cap electrodes with such electrically inert microporus structures to reduce interference alternatively such electrically inert microporous structures may be employed as u201c spacer u201d layers between stacked arrays of active electrodes as is discussed in example 2 in an alternative embodiment a porous spacer layer may be coated on top of the two sensor.