Patent ID: 8425841

Claim:
A test instrument, comprising: a substrate; a plurality of electrodes on the substrate; a cover; one or more spacing members arranged between the substrate and the cover; and a sample chamber defined between the cover and the substrate at top and bottom, the one or more spacing members defining sidewalls of the sample chamber, the sample chamber extending inwardly from an opening at an edge of the test instrument, the sidewalls of the one or more spacing members extending continuously from the opening to the plurality of electrodes, the sample chamber having a first portion and a second portion, the first portion located adjacent the opening and defined by tapered and curved sidewalls, the cover and the substrate, the second portion located inward of the first portion, the second portion of the sample chamber having a reagent and a smaller width than the first portion, and a vent from the second portion to outside of the test instrument, wherein the reagent is between the opening of the test instrument and the vent such that a sample of blood is drawn by capillary action from the opening of the test instrument to the reagent portion.