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

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

An electrochemical analyte sensor formed using conductive traces on a substrate can be used for determining and/or monitoring a level of analyte in in vitro or in vivo analyte-containing fluids. For example, an implantable sensor may be used for the continuous or automatic monitoring of a level of an analyte, such as glucose, lactate, or oxygen, in a patient. The electrochemical analyte sensor includes a substrate and conductive material disposed on the substrate, the conductive material forming a working electrode. In some sensors, the conductive material is disposed in recessed channels formed in a surface of the sensor. An electron transfer agent and/or catalyst may be provided to facilitate the electrolysis of the analyte or of a second compound whose level depends on the level of the analyte. A potential is formed between the working electrode and a reference electrode or counter/reference electrode and the resulting current is a function of the concentration of the analyte in the body fluid.

Electrochemical analyte sensor

Method of using a 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.

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

Tailoring the macroporosity and performance of sol-gel derived carbon composite glucose sensors

A new sol-gel-derived electrocatalytic carbon composite electrode was prepared by dispersing cobalt phthalocyanine (CoPC) in a carbon ceramic network. The performance of the CoPC-modified sol-gel carbon composite electrode compares favorably with that of common CoPC-containing carbon pastes in term of electrocatalytic properties and short- and long-term stability. The greatly improved stability and electrocatalytic action are illustrated in cyclic-voltammetric and flow injection amperometric measurements of hydrogen peroxide, hydrazine, oxalic acid, cysteine and thiourea. Such improvements are coupled with the versatility, mechanical stability and renewability features of sol-gel carbon composites.

Sol-gel-derived cobalt phthalocyanine-dispersed carbon composite electrodes for electrocatalysis and amperometric flow detection

Disposable complexing (preconcentrating) sensor strips for trace nickel have been fabricated by doping the screen-printed carbon ink with ligand dimethylglyoxime (DMG). The carbon ink is shown to be a useful matrix for incorporating the DMG, with the ligand maintaining its attractive coordination chemistry following the printing and firing processes. The response is characterized with respect to the ink composition, preconcentration period and potential, solution conditions and other variables. A short (30 s) accumulation period yields a detection limit of 5 μg/L nickel. The highly stable response indicates great promise for use as reusable devices. Measurement of nickel in a river water sample is demonstrated. Such incorporation of ligands into screen-printed carbon inks provides a promising route for thick-film sensors based on the preconcentration/voltammetric strategy.

Deog Su Park

Papers

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

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

Tailoring the macroporosity and performance of sol-gel derived carbon composite glucose sensors

Sol-gel-derived cobalt phthalocyanine-dispersed carbon composite electrodes for electrocatalysis and amperometric flow detection

Disposable nickel screen‐printed sensor based on dimethylglyoxime‐containing carbon ink