The present invention relates to an analyzing instrument comprising:a substrate (1)a plurality of electrodes (11,12,13) on the substratea cover (2)spacing means (3) arranged between the substrate and the cover, the spacing means (3) having mutually spaced portions anda sample chamber (4,5) defined between the cover (2) and the substrate (1) at top and bottom and the mutually spaced portions of the spacing means (3) at the sides the sample chamber (4,5) having a capillary (5) and a liquid pooling portion (4) that has curved side walls, that is in communication with the capillary (5) and that has a portion that is wider than the capillary (5).
