An analyte monitor includes a sensor, a sensor control unit, and a display unit. The sensor has, for example, a substrate, a recessed channel formed in the substrate, and conductive material disposed in the recessed channel to form a working electrode. The sensor control unit typically has a housing adapted for placement on skin and is adapted to receive a portion of an electrochemical sensor. The sensor control unit also includes two or more conductive contacts disposed on the housing and configured for coupling to two or more contact pads on the sensor. A transmitter is disposed in the housing and coupled to the plurality of conductive contacts for transmitting data obtained using the sensor. The display unit has a receiver for receiving data transmitted by the transmitter of the sensor control unit and a display coupled to the receiver for displaying an indication of a level of an analyte. The analyte monitor may also be part of a drug delivery system to alter the level of the analyte based on the data obtained using the sensor.

Analyte Monitoring Device And Methods Of Use

Polymers in sensor applications

The present invention relates generally to systems and methods for measuring an analyte in a host. More particularly, the present invention relates to systems and methods for transcutaneous measurement of glucose in a host.

Transcutaneous analyte sensor

A small diameter flexible electrode designed for subcutaneous in vivo amperometric monitoring of glucose is described. The electrode is designed to allow “one-point” in vivo calibration, i.e., to have zero output current at zero glucose concentration, even in the presence of other electroreactive species of serum or blood. The electrode is preferably three or four-layered, with the layers serially deposited within a recess upon the tip of a polyamide insulated gold wire. A first glucose concentration-to-current transducing layer is overcoated with an electrically insulating and glucose flux limiting layer (second layer) on which, optionally, an immobilized interference-eliminating horseradish peroxidase based film is deposited (third layer). An outer (fourth) layer is biocompatible.

Subcutaneous glucose electrode

A sensor designed to determine the amount and concentration of analyte in a sample having a volume of less than about 1 μL. The sensor has a working electrode coated with a non-leachable redox mediator. The redox mediator acts as an electron transfer agent between the analyte and the electrode. In addition, a second electron transfer agent, such as an enzyme, can be added to facilitate the electrooxidation or electroreduction of the analyte. The redox mediator is typically a redox compound bound to a polymer. The preferred redox mediators are air-oxidizable. The amount of analyte can be determined by coulometry. One particular coulometric technique includes the measurement of the current between the working electrode and a counter or reference electrode at two or more times. The charge passed by this current to or from the analyte is correlated with the amount of analyte in the sample. Other electrochemical detection methods, such as amperometric, voltammetric, and potentiometric techniques, can also be used. The invention can be used to determine the concentration of a biomolecule, such as glucose or lactate, in a biological fluid, such as blood or serum. An enzyme capable of catalyzing the electrooxidation or electroreduction of the biomolecule is provided as a second electron transfer agent.

Small volume in vitro analyte sensor

Enzymes usually cannot withstand the high-temperature curing associated with the thick-film fabrication process and require a separate immobilization step in connection with the production of single-use biosensors. We report on the development of sol−gel-derived enzyme-containing carbon inks that display compatibility with the screen-printing process. Such coupling of sol−gel and thick-film technologies offers a one-step fabrication of disposable enzyme electrodes, as it obviates the need for thermal curing. The enzyme-containing sol−gel carbon ink, prepared by dispersing the biocatalyst, along with the graphite powder and a binder, within the sol−gel precursors, is cured very rapidly (10 min) at low temperature (4 °C). The influence of the ink preparation conditions is explored, and the sensor performance is evaluated in connection with the incorporation of glucose oxidase or horseradish peroxidase. The resulting strips are stable for at least 3 months. Such sol−gel-derived carbon inks should serve as ho...

Screen-printable sol-gel enzyme-containing carbon inks.

Sol−gel processing is used for the first time for the preparation of electrochemical immunosensors. One-step sensor fabrication, based on the coupling of sol−gel and screen-printing technologies, is employed. A low-temperature cured ink is prepared by dispersion of rabbit immunoglobulin G (RIgG), graphite powder, and a binder in the sol−gel solution. The enzyme-labeled antibody can readily diffuse toward the encapsulated antigen, which retains its binding properties, and the association reaction is easily detected at the dispersed graphite surface. Use of anti-RIgG labeled with alkaline phosphatase, naphthyl phosphate as the substrate, and amperometric detection at +400 mV (vs Ag/AgCl) results in a low detection limit of 5 ng/mL (32 pM) for the solution antigen. Tailoring the porosity of the ceramic−carbon matrix can be used for tuning the assay performance. The high sensitivity, low cost, durability, and simplicity of the new single-use immunosensors make them well suited for various on-site applications.

Sol-gel-derived thick-film amperometric immunosensors.

The advantages which accrue from the coupling of sol-gel enzyme electrode preparation processes with the dispersion of electrocatalytic metal centers are described. In particular, ruthenium-dispersed sol-gel carbon thick-film bioelectrodes couple the low-temperature curing process with the elimination of contributions from easily oxidizable interfering species. The remarkable selectivity towards the glucose substrate is combined with a greatly enhanced sensitivity. Factors influencing the performance of these sol-gel-derived metal-doped enzyme strips are discussed.

Sol‐gel‐derived metal‐dispersed carbon composite amperometric biosensors

The preparation, characterization, and analytical utility of sol-gel-derived gold composite electrodes is described. The new metal-ceramic electrodes are comprised of gold powder homogeneously dispersed in a modified silica matrix. They couple the favorable electron-transfer kinetics common to gold surfaces with the regeneration, bulk modification, and versatility features of sol-gel-derived composite materials. The voltammetric characteristics of the composite gold-silica electrodes are explored and compared with conventional gold electrodes. Sol-gel-derived gold biosensors have been prepared by incorporating an oxidase enzyme within the sol-gel gold solution. Analogous thick-film enzyme strips, based on a new screen-printable gold biogel ink, have also been fabricated. To our knowledge, the above represent the first examples of metal-ceramic sensing electrodes and of bulk modification of metallic working electrodes.

Sol−Gel-Derived Gold Composite Electrodes

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

Prasad V. A. Pamidi

Papers

Screen-printable sol-gel enzyme-containing carbon inks.

Sol-gel-derived thick-film amperometric immunosensors.

Sol‐gel‐derived metal‐dispersed carbon composite amperometric biosensors

Sol−Gel-Derived Gold Composite Electrodes

Cross-linked enzyme matrix and uses thereof