2455results about "Immobilised enzymes" patented technology

Devices and methods for determining analyte levels are described. The devices and methods allow for the implantation of analyte-monitoring devices, such as glucose monitoring devices that result in the delivery of a dependable flow of blood to deliver sample to the implanted device. The devices include unique architectural arrangement in the sensor region that allows accurate data to be obtained over long periods of time.

The present invention relates generally to systems and methods for improved electrochemical measurement of analytes. The preferred embodiments employ electrode systems including an analyte-measuring electrode for measuring the analyte or the product of an enzyme reaction with the analyte and an auxiliary electrode configured to generate oxygen and / or reduce electrochemical interferants. Oxygen generation by the auxiliary electrode advantageously improves oxygen availability to the enzyme and / or counter electrode; thereby enabling the electrochemical sensors of the preferred embodiments to function even during ischemic conditions. Interferant modification by the auxiliary electrode advantageously renders them substantially non-reactive at the analyte-measuring electrode, thereby reducing or eliminating inaccuracies in the analyte signal due to electrochemical interferants.

A biosensor comprises a space part for sucking and housing a sample formed of two upper and lower plates, the two plates being stuck together by an adhesive layer, the space part for sucking and housing the sample being constituted so as to be partially opened in the peripheral part and partially closed by the adhesive layer, and has a working electrode having at least glucose oxidase immobilized thereon and a counter electrode on the same plane of the plate.

The present invention relates generally to systems and methods for increasing oxygen generation in electrochemical sensors in order to overcome the oxygen limitations. The preferred embodiments employ electrode systems with at least two electrodes in relatively close proximity to each other; wherein at least one electrode is configured to generate oxygen and at least one other electrode is configured to sense an analyte or a product of a reaction indicative of the concentration of analyte. The oxygen generated by the oxygen-generating electrode is available to the catalyst within a membrane system and / or the counter electrode, thereby enabling the electrochemical sensors of the preferred embodiments to function even during ischemic conditions.

Abstract of the DisclosureAn implantable analyte sensor including a sensing region for measuring the analyte and a non-sensing region for immobilizing the sensor body in the host. The sensor is implanted in a precisely dimensioned pocket to stabilize the analyte sensor in vivo and enable measurement of the concentration of the analyte in the host before and after formation of a foreign body capsule around the sensor. The sensor further provides a transmitter for RF transmission through the sensor body, electronic circuitry, and a power source optimized for long-term use in the miniaturized sensor body.

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.

An analyte-measuring device, particularly an electrochemical sensor, is provided for measuring current values at multiple bias potential settings to assess the quality of the analyte measurement, identify interference in the signal, and calculate substantially interference-free analyte concentration measurements. The device and method are suitable for calculating substantially interference-free analyte concentration measurements when glucose is the analyte and acetaminophen is an interfering species.

Systems and methods of use for continuous analyte measurement of a host's vascular system are provided. In some embodiments, a continuous glucose measurement system includes a vascular access device, a sensor and sensor electronics, the system being configured for insertion into communication with a host's circulatory system.

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.

Systems and methods of use for continuous analyte measurement of a host's vascular system are provided. In some embodiments, a continuous glucose measurement system includes a vascular access device, a sensor and sensor electronics, the system being configured for insertion into communication with a host's circulatory system.

Systems and methods of use for continuous analyte measurement of a host's vascular system are provided. In some embodiments, a continuous glucose measurement system includes a vascular access device, a sensor and sensor electronics, the system being configured for insertion into communication with a host's circulatory system.

An implantable analyte sensor including a sensing region for measuring the analyte and a non-sensing region for immobilizing the sensor body in the host. The sensor is implanted in a precisely dimensioned pocket to stabilize the analyte sensor in vivo and enable measurement of the concentration of the analyte in the host before and after formation of a foreign body capsule around the sensor. The sensor further provides a transmitter for RF transmission through the sensor body, electronic circuitry, and a power source optimized for long-term use in the miniaturized sensor body.

The present invention relates generally to devices for measuring an analyte in a host. More particularly, the present invention relates to devices for measurement of glucose in a host that incorporate a cellulosic-based interference domain.

The present invention provides a biointerface membrane for use with an implantable device that interferes with the formation of a barrier cell layer including; a first domain distal to the implantable device wherein the first domain supports tissue attachment and interferes with barrier cell layer formation and a second domain proximal to the implantable device wherein the second domain is resistant to cellular attachment and is impermeable to cells. In addition, the present invention provides sensors including the biointerface membrane, implantable devices including these sensors or biointerface membranes, and methods of monitoring glucose levels in a host utilizing the analyte detection implantable device of the invention. Other implantable devices which include the biointerface membrane of the present invention, such as devices for cell transplantation, drug delivery devices, and electrical signal delivery or measuring devices are also provided.

An electrochemical assay includes a method for determining with great accuracy the time at which an applied sample bridges a gap between the electrodes of an electrochemical cell. The method involves applying a constant small current across the gap, while monitoring the potential difference between the electrodes. The time at which the sample bridges the gap is marked by a sharp drop in the potential. A constant voltage is applied after the sample is detected, and the current and / or charge through the sample is monitored over a period of time. From the measured current or charge, the analyte concentration of interest can be calculated.

The present invention relates generally to systems and methods for increasing oxygen availability to implantable devices. The preferred embodiments provide a membrane system configured to provide protection of the device from the biological environment and / or a catalyst for enabling an enzymatic reaction, wherein the membrane system includes a polymer formed from a high oxygen soluble material. The high oxygen soluble polymer material is disposed adjacent to an oxygen-utilizing source on the implantable device so as to dynamically retain high oxygen availability to the oxygen-utilizing source during oxygen deficits. Membrane systems of the preferred embodiments are useful for implantable devices with oxygen-utilizing sources and / or that function in low oxygen environments, such as enzyme-based electrochemical sensors and cell transplantation devices.

A method for determining the concentration of a reduced (or oxidised) form of a redox species in an electrochemical cell of the kind comprising a working electrode and a counter electrode spaced from the working electrode by a predetermined distance, said method comprising the steps of: (1) applying an electric potential difference between the electrodes; (2) selecting the potential of the working electrode such that the rate of electro-oxidation of the reduced form (or electro-reduction of the oxidised form) of the species is diffusion controlled, (3) selecting the spacing between the working electrode and the counter electrode so that reaction products from the counter electrode arrive at the working electrode; (4) determining current as a function of time after application of the potential and prior to achievement of a steady state; (5) estimating the magnitude of the steady state current, and (6) obtaining from the change in current with time and the magnitude of the steady state current, a value indicative of the diffusion coefficient and / or of the concentration of the reduced form (or the oxidised form) of the species. Also disclosed is an apparatus for determining the concentration of a redox species in an electrochemical cell comprising: an electrochemical cell having a working electrode and a counter (or counter / reference) electrode, means for applying and electric potential difference between said electrodes, means for measuring the change in current with time, and characterised in that the working electrode is spaced from the counter electrode by less than 500 mum.

The present invention relates generally to systems and methods for improved electrochemical measurement of analytes. The preferred embodiments employ electrode systems including an analyte-measuring electrode for measuring the analyte or the product of an enzyme reaction with the analyte and an auxiliary electrode configured to generate oxygen and / or reduce electrochemical interferants. Oxygen generation by the auxiliary electrode advantageously improves oxygen availability to the enzyme and / or counter electrode; thereby enabling the electrochemical sensors of the preferred embodiments to function even during ischemic conditions. Interferant modification by the auxiliary electrode advantageously renders them substantially non-reactive at the analyte-measuring electrode, thereby reducing or eliminating inaccuracies in the analyte signal due to electrochemical interferants.

An apparatus for detection and quantitation of an electrochemically-detect- able analyte, such as glucose, in blood or interstitial fluid includes a meter unit, a lancet and an electrochemical sensor. Of these components, the meter is preferably reusable, while the lancet and the electrochemical sensor are preferably incorporated in assemblies intended for single-use. The meter unit has a housing, within which a lancet is engaged with a mechanism for moving then lancet; a connector disposed within the housing for engaging an electrochemical sensor specific for the analyte and transmitting a signal indicative of the amount of analyte, and a display operatively-associated with a connector for displaying the amount of the analyte to user. The electrochemical sensor is adapted for detection of a particular analyte. In addition, the electrochemical sensor has an absorptive member for uptake of a sample of blood or interstitial fluid. In one version, the lancet moves from a initial position to a piercing position in which skin of the user is pierced and optionally back to a retracted position. The electrochemical sensor is disposed such that the absorptive member takes up a sample from the pierced skin of the user when it is pierced by the lancet without movement of the apparatus. In an alternative version, the lancet is a hollow cannula through which blood or interstitial fluid is transported from the puncture site to an absorbent portion of the electrochemical sensor. In either version, the apparatus provides single-step operation in which sample acquisition and analysis occur as a result of the single action of pressing the apparatus against the users skin.

A sensor, and methods of making, for determining the concentration of an analyte, such as glucose or lactate, in a biological fluid such as blood or serum, using techniques such as coulometry, amperometry, and potentiometry. The sensor includes a working electrode and a counter electrode, and can include an insertion monitoring trace to determine correct positioning of the sensor in a connector.

A multifunctional membrane is provided. The multifunctional membrane is suitable for use in an analyte sensor. In a particular application, the multifunctional membrane may be used in connection with an amperometric biosensor, such as a transcutaneous amperometric biosensor. Some functions of the membrane are associated with properties of membrane itself, which is comprised of crosslinked polymers containing heterocyclic nitrogen groups. For example, the membrane, by virtue of its polymeric composition, may regulate the flux of an analyte to a sensor. Such regulation generally improves the kinetic performance of the sensor over a broad range of analyte concentration. Other functions of the membrane are associated with functional components, such as a superoxide-dismutating / catalase catalyst, either in the form of an enzyme or an enzyme mimic, that can be bound to the scaffold provided by the membrane. The effect of any such enzyme or enzyme mimic is to lower the concentration of a metabolite, such as superoxide and / or hydrogen peroxide, in the immediate vicinity of the sensing layer of the biosensor. Lowering the concentrations of such metabolites, which are generally deleterious to the function of the sensor, generally protects or enhances biosensor integrity and performance. The membrane is thus an important tool for use in connection with analyte sensors, amperometric sensors, biosensors, and particularly, transcutaneous biosensors. A membrane-covered sensor and a method for making same are also provided.

Abstract of the DisclosureAn implantable analyte sensor including a sensing region for measuring the analyte and a non-sensing region for immobilizing the sensor body in the host. The sensor is implanted in a precisely dimensioned pocket to stabilize the analyte sensor in vivo and enable measurement of the concentration of the analyte in the host before and after formation of a foreign body capsule around the sensor. The sensor further provides a transmitter for RF transmission through the sensor body, electronic circuitry, and a power source optimized for long-term use in the miniaturized sensor body.

An implantable biosensor assembly and system includes an enzymatic sensor probe from which subcutaneous and interstitial glucose levels may be inferred. The assembly may be associated by direct percutaneous connection with electronics, such as for signal amplification, sensor polarization, and data download, manipulation, display, and storage. The biosensor comprises a miniature probe characterized by lateral flexibility and tensile strength and has large electrode surface area for increased sensitivity. Irritation of tissues surrounding the probe is minimized due to ease of flexibility and small cross section of the sensor. Foreign body reaction is diminished due to a microscopically rough porous probe surface.

An analyte sensor for use in connection with a biofluid is described. The analyte sensor may comprise any suitable interface between the biofluid and a derivative of the biofluid and any suitable transducer of information concerning an analyte. At least one catalytic agent is provided in a locale or vicinity of the interface. The catalytic agent, such as a proteinaceous agent or a non-proteinaceous, organic-metal agent, is sufficient to catalyze the degradation of reactive oxygen and / or nitrogen species that may be present in the vicinity of the interface. An analyte-sensing kit and a method of sensing an analyte are also described.

The present invention relates generally to systems and methods for increasing oxygen generation in electrochemical sensors in order to overcome the oxygen limitations. The preferred embodiments employ electrode systems with at least two electrodes in relatively close proximity to each other; wherein at least one electrode is configured to generate oxygen and at least one other electrode is configured to sense an analyte or a product of a reaction indicative of the concentration of analyte. The oxygen generated by the oxygen-generating electrode is available to the catalyst within a membrane system and / or the counter electrode, thereby enabling the electrochemical sensors of the preferred embodiments to function even during ischemic conditions.

Devices and methods are provided for continuous measurement of an analyte concentration. The device can include a sensor having a plurality of sensor elements, each having at least one characteristic that is different from other sensor(s) of the device. In some embodiments, the plurality of sensor elements are each tuned to measure a different range of analyte concentration, thereby providing the device with the capability of achieving a substantially consistent level of measurement accuracy across a physiologically relevant range. In other embodiments, the device includes a plurality of sensor elements each tuned to measure during different time periods after insertion or implantation, thereby providing the sensor with the capability to continuously and accurately measure analyte concentrations across a wide range of time periods. For example, a sensor system 180 is provided having a first working electrode 150 comprising a first sensor element 102 and a second working electrode 160 comprising a second sensor element 104, and a reference electrode 108 for providing a reference value for measuring the working electrode potential of the sensor elements 102, 104.