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ANALYTE SENSORS AND METHODS OF USE
BACKGROUND
Continuous analyte monitoring systems such as continu- 5 ous glucose monitoring systems use analyte sensors a portion of which is placed in contact with the patient's bodily fluid such as interstitial fluid or blood. The analyte sensor such as glucose sensors are configured with electrodes such as a working electrode, a counter electrode and a reference elec- 10 trode, and where at least a portion of the sensor is placed in vivo so as to detect the level of the patient's analyte. In the three electrode configuration, the reference electrode is maintained substantially current free, and is configured to establish a substantially constant electrical potential difference with 15 respect to the working electrode. The electrical potential difference then is used to drive certain electrochemical reactions that result in a current signal which is directly proportional to the level of analyte in the patient (such as the patient's glucose concentration). 20
The analyte sensor configuration described above, and in most glucose sensors that employ multiple electrodes for detecting the glucose level, for example, the counter electrode is generally configured to close the circuit. That is, since the electrons resulting from the electrochemical reactions by the 25 analyte sensor are flowing into the working electrode from the electrolyte solution (the patient's body), the counter electrode of the analyte sensor needs to dispose of the electrons back into the electrolyte (that is, the counter electrode must find molecules or ions that can be reduced). The applied electrical 30 potential at the counter electrode is regulated through a feedback loop such that the necessary reduction reactions can take place. Therefore, it is necessary for the counter electrode of the analyte sensor be electrically coupled to the human body.
In view of the foregoing, it would be desirable to have 35 methods and device for providing a compact, cost effective analyte sensor configuration. Indeed, it would be desirable to have methods and device for providing analyte sensors with external counter electrode which is not placed in vivo along with the working and reference electrodes of the analyte 40 sensor so as to be in fluid contact with the patient's analyte. Moreover, it would be desirable to have method and system for manufacturing analyte sensors to achieve cost effectiveness and scalability by, for example, reducing the number of necessary manufacturing steps. 45
SUMMARY OF THE INVENTION
In view of the foregoing, in accordance with the various embodiments of the present invention, there is provided 50 methods and devices for analyte sensor configuration with an external on-body counter electrode forming a two electrode analyte sensor such as glucose sensors, which is provided with the working and reference electrodes at least a portion of each of which are placed in fluid contact with the patient's 55 analyte, and which is provided with an external non-invasive counter electrode provided on the patient's skin.
These and other objects, features and advantages of the present invention will become more fully apparent from the following detailed description of the embodiments, the 60 appended claims and the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 illustrates a data monitoring and management sys- 65 tern such as, for example, an analyte monitoring system 100 for practicing one embodiment of the present invention;
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FIG. 2 is a block diagram of the transmitter unit of the data monitoring and detection system shown in FIG. 1 in accordance with one embodiment of the present invention;
FIGS. 3A-3B illustrate a bottom view of the transmitter unit housing with counter electrode contact in accordance with one embodiment of the present invention;
FIGS. 4A-4C each illustrates the transmitter unit coupled with an analyte sensor with external counter electrode in accordance with various alternate embodiments of the present invention;
FIGS. 5A and 5B illustrate the side cross-sectional view and bottom view of the transmitter unit coupled with an analyte sensor with external counter electrode with dislocation detection mechanism in accordance with one embodiment of the present invention;
FIG. 6A illustrates a two working electrode analyte sensor with external counter electrode, FIG. 6B illustrates a three working electrode analyte sensor with external counter electrode in accordance with various embodiments of the present invention, and FIG. 6C illustrates a two working electrode analyte sensor with external counter electrode of another embodiment; and
FIG. 7 illustrates a cross sectional view of a two sided analyte sensor with external counter electrode in accordance with one embodiment of the present invention.
DETAILED DESCRIPTION
FIG. 1 illustrates a data monitoring and management system such as, for example, an analyte monitoring system 100 for practicing one embodiment of the present invention. In such embodiment, the analyte monitoring system 100 includes an analyte sensor 101, a transmitter unit 102 coupled to the sensor 101, and a receiver unit 104 which is configured to communicate with the transmitter unit 102 via a communication link 103. The receiver unit 104 may be further configured to transmit data to a data processing terminal 105 for evaluating the data received by the receiver unit 104.
Only one sensor 101, transmitter unit 102, communication link 103, receiver unit 104, and data processing terminal 105 are shown in the embodiment of the analyte monitoring system 100 illustrated in FIG. 1. However, it will be appreciated by one of ordinary skill in the art that the analyte monitoring system 100 may include one or more sensor 101, transmitter unit 102, communication link 103, receiver unit 104, and data processing terminal 105, where each receiver unit 104 is uniquely synchronized with a respective transmitter unit 102. Moreover, within the scope of the present invention, the analyte monitoring system 100 may be a continuous monitoring system, or a semi-continuous or discrete monitoring system.
In one embodiment of the present invention, the sensor 101 is physically positioned on the body of a user whose analyte level is being monitored. The sensor 101 maybe configured to continuously sample the analyte level of the user and convert the sampled analyte level into a corresponding data signal for transmission by the transmitter unit 102. In one embodiment, the transmitter unit 102 is mounted on the sensor 101 so that both devices are positioned on the user's body. The transmitter unit 102 performs data processing such as filtering and encoding on data signals, each of which corresponds to a sampled glucose level of the user, for transmission to the receiver unit 104 via the communication link 103.
Additional analytes that may be monitored or determined by sensor 101 include, for example, acetyl choline, amylase, bilirubin, cholesterol, chorionic gonadotropin, creatine kinase (e.g., CK-MB), creatine, DNA, fructosamine, glucose, glutamine, growth hormones, hormones, ketones, lactate,
