An electrode assembly for polarographic assay of glucose in solution having a laminated membrane, the outer membrane being from 1 to 20 .mu.m thick and having a pore size of 10 to 125 .ANG., the inner membrane having a thickness of 2 to 4 .mu.m, and bonded to the outer membrane with immobilized glucose oxidase. Rapid assays are carried out by measuring the current difference before equilibrium is attained and at least 5 seconds after initial contact of sample with the outer membrane.
A sensor of the enzyme-electrode type comprising an electrode and a membrane permeable to liquids and solutes which is positioned between the electrode and a specimen containing the analyte to be determined, is characterized by the fact that a layer of a porous material, positioned in the membrane between the enzyme-containing layer and the specimen, has been treated to at least partially fill the pores with a liquid of limited volatility which is not significantly soluble in water and is to some degree a solvent for the analyte.
Degradation of multielectrochemical sensors in a common flow stream is averted by positioning any sensors having as its associated enzyme an oxidoreductase enzyme capable of producing, as a result interaction with its respective substrate, an oxidizing agent downstream of the other enzyme sensors not having such oxidoreductase enzyme.
Homogeneous membranes permeable to oxygen and glucose composed of hydrophilic polyurethanes that are capable of absorbing from 10 to 50% of their dry weight of water. Variations in the composition of the hydrophilic polyurethanes make possible the fabrication of membranes in which the ratios of the diffusion coefficients of oxygen to glucose can be varied over a wide range. These membranes can be used in the fabrication of an electrochemical glucose sensor intended for use in vivo as an aid in the treatment of diabetes mellitus.
A method of sensing blood glucose levels in the steps of passing glucose from a peritoneal fluid through a semi-permeable membrane and into a closed chamber, metabolizing the passed glucose in the closed chamber with a yeast suspension to produce a level of carbon dioxide and detection of the level of carbon dioxide, and controlled insulin infusion into blood as a consequence of detected carbon dioxide level. Implantable apparatus is also provided for carrying out the method within a body of live tissue.
Improved Newman type enzyme containing laminated membranes are disclosed for use in conjunction with polarographic cells to measure analyte concentration in solutions. The laminated membranes comprise a semipermeable outer, support layer including super large pores of greater than about 200 .ANG. in diameter. The outer layer preferably comprises pore sizes of about 380-750 .ANG. in diameter and has a percentage porosity of about 0.005-0.2%.
