Patent ID: 7198708

Claim:
An electrochemical biosensor for quantifying one or more redox species originally present in a liquid sample comprising a background electrochemical activity, wherein said biosensor does not employ a enzymatic mediator means for detection of the redox species or a wet electrode arrangement and comprises: i) an electrode system comprising a single working electrode, a counter electrode and a reference electrode, wherein the counter electrode and reference electrode may be optionally combined; ii) a filter means comprising a sample loading position, said filter means being either directly affixed to and in intimate contact with a charge transfer surface of the working electrode or directly affixed to and in intimate contact with an intermediate layer which is directly affixed to and in intimate contact with the charge transfer surface of the working electrode without an intervening wet electrolyte phase; wherein said filter means separates said sample loading position from said charge transfer surface by an amount of filter material capable of providing a tangential peak height for said background electrochemical activity of ICSS than 30% of the tangential peak height for said redox species; and wherein the redox species originally present in the liquid sample is quantified by direct electrochemical reaction with the charge transfer surface of the working electrode and is not generated by an enzymatic mediator during the measurement process.