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 telemetered characteristic monitor system includes a remotely located data receiving device, a sensor for producing signal indicative of a characteristic of a user, and a transmitter device. The transmitter device includes a housing, a sensor connector, a processor, and a transmitter. The transmitter receives the signals from the sensor and wirelessly transmits the processed signals to the remotely located data receiving device. The processor coupled to the sensor processes the signals from the sensor for transmission to the remotely located data receiving device. The data receiving device may be a characteristic monitor, a data receiver that provides data to another device, an RF programmer for a medical device, a medication delivery device (such as an infusion pump), or the like.

Telemetered characteristic monitor system and method of using the same

Electrochemical sensors based on conducting polymer—polypyrrole

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

An apparent direct electron transfer between various electrode materials and peroxidases immobilized on the surface of the electrode has been reported in the last few years. An electrocatalytic reduction of hydrogen peroxide stars at about +600 mV versus a saturated calomel (reference) electrode (SCE) at neutral pH. The efficiency of the electrocatalytic current increases as the applied potential is made more negative and starts to level off at about –200 mV versus SCE. Amperometric biosensors for hydrogen peroxide can be constructed with these types of peroxidase modified electrodes. By co-immobilizing a hydrogen peroxide-producing oxidase with the peroxidase, amperometric biosensors can be made that respond to the substrate of the oxidase within a potential range essentially free of interfering electrochemical reactions. Examples of glucose, alcohol and amino acid sensors are shown.

Amperometric biosensors based on an apparent direct electron transfer between electrodes and immobilized peroxidases. Plenary lecture

An apparent direct electron transfer between various electrode materials and peroxidases immobilized on the surface of the electrode has been reported in the last few years. An electrocatalytic reduction of hydrogen peroxide promoted by the immobilized peroxidase starts already at about +600 mV vs SCE at neutral pH. The efficiency of the electrocatalytic current increases as the applied potential is made more negative and starts to level off at about -200 mV vs SCE. Amperometric biosensors for hydrogen peroxide can be constructed with these kind of peroxidase modified electrodes. By co-immobilizing a hydrogen peroxide producing oxidase with the peroxidase, amperometric biosensors can be made responding for the substrate of the oxidase within a potential range essentially free of interfering electrochemical reactions. Sensors for L- and D-amino acids are shown with preliminary results obtained for L- and D-phenylalanine, respectively.

Amperometric biosensors for detection of L‐ and D‐amino acids based on coimmobilized peroxidase and L‐ and D‐amino acid oxidases in carbon paste electrodes

A reagentless amperometric biosensor for alcohol detection in column liquid chromatography based on co-immobilized peroxidase and alcohol oxidase in carbon paste.

Enzyme-based biosensor as a selective detection unit in column liquid chromatography

This paper describes a fully automated on-line system for the unattended monitoring of bioprocesses. Removal of solids and macromolecules from fermentation broth is achieved with a tangential flow filtration unit (Waters Filter/Acquisition Module). The obtained filtrate is transported in a flow system to a cleanup step, based on solid-phase extraction, followed by introduction into a column liquid chromatographic system. Carbohydrates are then detected by refractive index and ethanol content usings laboratory-made selective amperometric alcohol biosensor

Kristina Johansson

Papers

Amperometric biosensors based on an apparent direct electron transfer between electrodes and immobilized peroxidases. Plenary lecture

Amperometric biosensors for detection of L‐ and D‐amino acids based on coimmobilized peroxidase and L‐ and D‐amino acid oxidases in carbon paste electrodes

A reagentless amperometric biosensor for alcohol detection in column liquid chromatography based on co-immobilized peroxidase and alcohol oxidase in carbon paste.

Enzyme-based biosensor as a selective detection unit in column liquid chromatography

On-line fermentation process monitoring of carbohydrates and ethanol using tangential-flow filtration and column liquid chromatography