DEFINING AN ELECTRODE AREA

摘要

The present invention relates to a method for defining an area (4) of a laye r on a porous substrate comprising compressing a volume of the substrate to produce a compressed region (8) which defines, or which in combination with an edge (7) of the substrate or of the layer defines, a boundary of the area and which substantially prevents the transpo rt of material through or across its surface. The present invention also relates to an electrochemical sensing device comprising: a porous substrate; and an electrode (1) on one side of the substrate; wherein a region of the substrate is compressed to an extent which forms a barrier t o migration of electrolyte within the substrate, the compressed region defining, or in combination with an edge of the substrate or the electrode defining, a zone on the electrode of predetermined area.