Diagnostic test strip

A test strip device for measuring an analyte in a liquid sample consisting essentially of relative to a horizontal plane,

• a) a top support layer which provides support to the test strip device, such layer having a sample receiving port therein,
• b) a spreading screen physically attached to said top layer and located directly below said sample receiving port whereby sample applied at said port encounters said screen, wherein said screen has mesh openings sufficient in size
• i) to act as a retaining screen for said sample until substantially all of such screen in said port has been contacted with said sample, and
• ii) to allow the sample to proceed vertically through the screen in a uniform flow,
• c) a screen mesh separating layer adjacent to and in contact spreading screen in vertical alignment with said sample port, said layer having fixed thereon an agent capable of capturing red blood cells,
• d) a reaction membrane having a surface which is in direct physical contact with said separation layer, said reaction membrane
• i) being capable of excluding red blood cells from a liquid sample containing the same, and
• ii) having reactants and an indicator system incorporated within its matrix capable of reacting with the analyte of interest in the sample and causing a color change at the reaction membrane which is a measure of the presence or amount of analyte in the sample, and
• e) a bottom support layer in physical contact with said reaction membrane and which provides support to the test strip device, said layer having a reaction viewing opening in vertical alignment with the sample receiving port.