Abstract: An electrochemical sensor system and membrane and method thereof for increased accuracy and effective life of electrochemical and enzyme sensors.

Abstract: A fractionation system for providing a clarified fraction or a fraction for analysis of biological fluids and the like includes a disposable filtration vessel with a first reservoir chamber adapted to receive the fluid to be fractionated, a second reservoir chamber and a flow channel that extends between the reservoir chambers. The lower surface of the flow channel is defined by a microporous sheet membrane, and collection structure is disposed on the side of the membrane opposite the flow channel. Low gas pressure (less than ten psi) applied alternately to liquid surfaces in the reservoir chambers produced reciprocating flow of the fluid between the reservoir chambers in a wide thin stream through the flow channel with resulting collection of a fraction of the liquid material that passes through the membrane. A one-half milliliter volume of plasma from a two milliliter volume sample of blood is obtained with the system in less than one minute without any discernible hemolysis.