Abstract: A dry reagent composition that includes an active redox enzyme that oxidizes an analyte as a specific substrate to produce an inactive reduced form of the enzyme; and a salt of ferricyanide provides improved performance in electrochemical test strips such as those used for detection of glucose. The salt of ferricyanide consists of ferricyanide and positively-charged counter ions, and the positively charged counter ions are selected such that the salt of ferricyanide is soluble in water, and such that the salt of ferricyanide or the crystalline phase of the salt of ferricyanide has a solubility in water and/or a lower E0eff at a concentration of 100 mM than potassium ferricyanide. For example, the salt of ferricyanide may be tetramethylammonium ferricyanide.

Abstract: A method for obtaining information encoded on an electrochemical test strip is provided. The test strip has two electrodes disposed within a sample space and the information is encoded on the test strip prior to introduction of liquid sample. The method includes the step of introducing sample to the sample space so that the sample is in contact with the two electrodes within the sample space. In another step a value is determined that is representative of the double layer capacitance of the test strip and/or the equivalent capacitance of the test strip. The determined value is then translated into information reflecting a characteristic of the test strip prior to introduction of sample.

Abstract: The presence of oxygen or red blood cells in a sample applied to an electrochemical test strip that makes use of a reduced mediator is corrected for by an additive correction factor that is determined as a function of the temperature of the sample and a measurement that reflects the oxygen carrying capacity of the sample. The measured oxygen carrying capacity can also be used to determine hematocrit and to distinguish between blood samples and control solutions applied to a test strip.

Abstract: A test strip and analytical apparatus have pin connections permitting the definition of geographic regions or of particular customers. A test strip made for use in a particular region or for a particular customer will have pin connections matching features of the apparatus made for use in that region or by that customer. Insertion of the strip into the apparatus does not merely turn on the apparatus, but provides the regional or customer coding. Analog switches within the apparatus allow coding of a larger number of distinct regions or customers than would otherwise be possible, all without degrading the quality of the measurements made of the fluid being tested. Conductive paths in the strips permit testing the strips during manufacture so as to detect quality lapses regarding the printing or deposition of the paths.

Abstract: An electrochemical test device is provided having a base layer with a first electrode thereon and a top layer with a second electrode thereon. The two electrodes are separated by a spacer layer having an opening therein, such that a sample-receiving space is defined with one electrode on the top surface, the other electrodes on the bottom surface and side walls formed from edges of the opening in the spacer. Reagents for performing the electrochemical reaction are deposited on one of the electrodes and on the side walls of the sample-receiving space.

Abstract: The ability to switch at will between amperometric measurements and potentiometric measurements provides great flexibility in performing analyses of unknowns. Apparatus and methods can provide such switching to collect data from an electrochemical cell. The cell may contain a reagent disposed to measure glucose in human blood.

Abstract: A dry reagent composition that includes an active redox enzyme that oxidizes an analyte as a specific substrate to produce an inactive reduced form of the enzyme; and a salt of ferricyanide provides improved performance in electrochemical test strips such as those used for detection of glucose. The salt of ferricyanide consists of ferricyanide and positively-charged counter ions, and the positively charged counter ions are selected such that the salt of ferricyanide is soluble in water, and such that the salt of ferricyanide or the crystalline phase of the salt of ferricyanide has a solubility in water and/or a lower E0eff at a concentration of 100 mM than potassium ferricyanide. For example, the salt of ferricyanide may be tetramethylammonium ferricyanide.

Abstract: The presence of oxygen or red blood cells in a sample applied to an electrochemical test strip that makes use of a reduced mediator is corrected for by an additive correction factor that is determined as a function of the temperature of the sample and a measurement that reflects the oxygen carrying capacity of the sample. The measured oxygen carrying capacity can also be used to determine hematocrit and to distinguish between blood samples and control solutions applied to a test strip.

Abstract: A dry reagent composition that includes an active redox enzyme that oxidizes an analyte as a specific substrate to produce an inactive reduced form of the enzyme; and a salt of ferricyanide provides improved performance in electrochemical test strips such as those used for detection of glucose. The salt of ferricyanide consists of ferricyanide and positively-charged counter ions, and the positively charged counter ions are selected such that the salt of ferricyanide is soluble in water, and such that the salt of ferricyanide or the crystalline phase of the salt of ferricyanide has a solubility in water and/or a lower E0eff at a concentration of 100 mM than potassium ferricyanide. For example, the salt of ferricyanide may be tetramethylammonium ferricyanide.

Abstract: The presence of oxygen or red blood cells in a sample applied to an electrochemical test strip that makes use of a reduced mediator is corrected for by an additive correction factor that is determined as a function of the temperature of the sample and a measurement that reflects the oxygen carrying capacity of the sample. The measured oxygen carrying capacity can also be used to determine hematocrit and to distinguish between blood samples and control solutions applied to a test strip.

Abstract: The present invention provides a method and apparatus for creating test strips that may be identified based on differences in electrical conduction or resistance between contact point on the test strip. This is achieved by creating a base test strip with contact points that may be connected to other contact points by an electrical connection. These base test strips may be modified to create a difference in electrical conductivity between contact points, or a contact point may be eliminated. This modification can be used to distinguish different types of test strips based on electrical signature. Additionally, the base test strip may be created such that multiple modifications are possible to distinguish numerous characteristics of test strips.

Abstract: A test meter for receiving a test strip comprises: (a) a housing; (b) electronic circuitry disposed within the housing and (c) a strip port connector connected to the electronic circuitry and extending to an opening in the housing, said strip port connector connecting the electronic circuitry with a received test strip. The strip port connector contains a pair of top and bottom contacts, said top and bottom contacts having a proximal end and a distal end and a central contact portion, the top and bottom contacts of the pair are transversely aligned with one another; and the distal ends of the top and bottom contacts are separated or separable from one another by insertion of a test strip between the opposed contacts. The contacts and the meter are adapted to permit detection of faulty contacts and/or coding associated with an inserted test strip.

Abstract: A method for monitoring a select analyte in a sample in an electrochemical system. The method includes applying to the electrochemical system a time-varying potential superimposed on a DC potential to generate a signal; and discerning from the signal a contribution from the select analyte by resolving an estimation equation based on a Faradaic signal component and a nonfaradaic signal component.

Abstract: Correction for initial variation in thickness of a polymer layer and for changes in the coating thickness that occur after implantation of a biosensor and therefore provides substantial increase in the accuracy and lifetime of implantable sensors is done using a factor derived from the decay of potential.

Abstract: A test strip with an incorporated optical waveguide and deflectors punched through the optical waveguide allows light to exit through a layer of the test strip and be detected by a photo detector. Using light and a photodetector, these uniquely coded strips are identified. The waveguide can be constructed by sandwiching two layers of the test strip around a light transmissible layer. This configuration allows light to be transmitted through the test strip and out the other end, as well as allowing some light to escape the deflector. This light is detected by a photodetector mounted in the analyte test meter. The deflectors may be placed in patterns such that detection of this light indicates certain characteristics of the strip, such as non-counterfeit, regional identification, type of analyte tested, and coding information.

Abstract: A method for obtaining information encoded on an electrochemical test strip is provided. The test strip has two electrodes disposed within a sample space and the information is encoded on the test strip prior to introduction of liquid sample. The method includes the step of introducing sample to the sample space so that the sample is in contact with the two electrodes within the sample space. In another step a value is determined that is representative of the double layer capacitance of the test strip and/or the equivalent capacitance of the test strip. The determined value is then translated into information reflecting a characteristic of the test strip prior to introduction of sample.

Abstract: Electrochemical test cells are made with precision and accuracy by adhering an electrically resistive sheet having a bound opening to a first electrically conductive sheet. A notching opening is then punched through the electrically resistive sheet and the first electrically conductive sheet. The notching opening intersects the first bound opening in the electrically resistive sheet, and transforms the first bound opening into a notch in the electrically resistive sheet. A second electrically conductive sheet is punched to have a notching opening corresponding to that of first electrically conductive sheet, and this is adhered to the other side of the electrically resistive sheet such that the notching openings are aligned. This structure is cleaved from surrounding material to form an electrochemical cell that has a sample space for receiving a sample defined by the first and second conductive sheets and the notch in the electrically resistive sheet.

Abstract: A method for obtaining information encoded on an electrochemical test strip is provided. The test strip has two electrodes disposed within a sample space and the information is encoded on the test strip prior to introduction of liquid sample. The method includes the step of introducing sample to the sample space so that the sample is in contact with the two electrodes within the sample space. In another step a value is determined that is representative of the double layer capacitance of the test strip and/or the equivalent capacitance of the test strip. The determined value is then translated into information reflecting a characteristic of the test strip prior to introduction of sample.

Abstract: Correction for initial variation in thickness of a polymer layer and for changes in the coating thickness that occur after implantation of a biosensor and therefore provides substantial increase in the accuracy and lifetime of implantable sensors is done using a factor derived from the decay of potential.

Abstract: A method and apparatus for electrochemical detection of analyte in a sample makes use of a binding interaction and relies on the discovery that asymmetric distribution of a redox enzyme between two electrodes that occurs when a redox enzyme-containing reagent is immobilized at the surface of one electrode can be detected as a chemical potential gradient arising from an asymmetry in the distribution of oxidized or reduced redox substrate. This chemical potential gradient can be detected potentiometrically by observing the potential difference between the electrodes in an open circuit, or amperometrically by observing the current flow between the electrodes when the circuit is closed. In both cases, the observation of asymmetry can be done without the application of an external potential or current to the electrodes.