Chemistry: analytical and immunological testing – Heterocyclic carbon compound – Hetero-o
Reexamination Certificate
2002-11-01
2004-06-01
Wallenhorst, Maureen M. (Department: 1743)
Chemistry: analytical and immunological testing
Heterocyclic carbon compound
Hetero-o
C436S149000, C436S150000, C436S014000, C422S082010, C422S082020, C435S014000, C204S403010, C204S403040, C204S403110
Reexamination Certificate
active
06743635
ABSTRACT:
BACKGROUND
1. Field of the Invention
The present invention relates to electrochemical sensors and, more particularly, to systems and methods for sensing blood glucose levels electrochemically.
2. Description of Related Art
Many people, such as diabetics, have a need to monitor their blood glucose levels on a daily basis. A number of systems that allow people to conveniently monitor their blood glucose levels are available. Such systems typically include a test strip where the user applies a blood sample and a meter that “reads” the test strip to determine the glucose level in the blood sample.
Among the various technologies available for measuring blood glucose levels, electrochemical technologies are particularly desirable because only a very small blood sample may be needed to perform the measurement. In electrochemical-based systems, the test strip typically includes a sample chamber that contains reagents, such as glucose oxidase and a mediator, and electrodes. When the user applies a blood sample to the sample chamber, the reagents react with the glucose, and the meter applies a voltage to the electrodes to cause a redox reaction. The meter measures the resulting current and calculates the glucose level based on the current.
It should be emphasized that accurate measurements of blood glucose levels may be critical to the long-term health of many users. As a result, there is a need for a high level of reliability in the meters and test strips used to measure blood glucose levels. However, as sample sizes become smaller, the dimensions of the sample chamber and electrodes in the test strip also become smaller. This, in turn, may make test strips become more sensitive to smaller manufacturing defects and to damage from subsequent handling.
Accordingly, there is a need to provide blood glucose measuring systems and methods with features for measuring blood glucose levels conveniently and reliably.
SUMMARY
In a first principal aspect, the present invention provides a test strip for testing a blood sample. The test strip comprises a sample chamber for the blood sample, at least four electrodes for measuring at least one electrical characteristic of the blood sample in the sample chamber, a plurality of electrical contacts electrically connected to the at least four electrodes, and at least one auto-on electrical contact electrically isolated from the at least four electrodes. The at least four electrodes include a working electrode, a counter electrode, a fill-detect anode, and a fill-detect cathode.
In a second principal aspect, the present invention provides a method of making a plurality of test strips. In accordance with the method, a plurality of test strip structures are formed on one sheet, and the test strip structures are separated into test strips. Each of the test strip structures includes a sample chamber, a plurality of electrodes (including a working electrode, a counter electrode, a fill-detect anode, and a fill-detect cathode), a plurality of electrical contacts electrically connected to the electrodes, and at least one auto-on electrical contact electrically isolated from the plurality of electrodes.
In a third principal aspect, the present invention provides a method of using a test strip to test a blood sample. The test strip includes a sample chamber, a working electrode, a counter electrode, a pair of fill-detect electrodes, and an auto-on conductor. In accordance with the method, the test strip is inserted into a meter that is in a sleep mode. The meter detects an auto-on current through the auto-on conductor and responsively enters an active mode. The blood sample is applied to the sample chamber. The meter detects the blood sample in the sample chamber by applying a fill-detect voltage between the fill-detect electrodes and measuring a fill-detect current flowing between the fill-detect electrodes. The meter applies an assay voltage between the working and counter electrodes and makes at least one measurement of the resulting current. The meter determines a test result from the at least one current measurement.
In a fourth principal aspect, the present invention provides a method of strip identification. A strip that includes an auto-on conductor is inserted into a meter that is in a sleep mode. The meter detects the strip by detecting a current flow through the auto-on conductor, and responsively enters an active mode. The meter measures a voltage drop across the auto-on conductor and identifies the strip as either a test strip or a check strip based on the voltage drop. If the strip is a test strip, the meter performs a test strip sequence. If the strip is a check strip, the meter performs a check strip sequence.
In a fifth principal aspect, the present invention provides a removable data storage device for a meter that uses test strips to measures glucose levels in blood samples. The removable data storage device comprises a carrier, a circuit board mounted to the carrier, and a memory mounted to the circuit board. The carrier has a proximal end and a distal end and is keyed for inserting the distal end into the meter in a preferred orientation. The circuit board includes a plurality of electrical contacts for electrically connecting to the meter. The plurality of electrical contacts includes a ground contact and a voltage supply contact. The ground contact extends closer to the distal end than the voltage supply contact. The memory stores data for use by the meter, including calibration coefficients for a plurality of test strips. The memory is electrically connected to the plurality of electrical contacts on the circuit board. When the removable data storage device is inserted into the meter in the preferred orientation, the ground contact becomes electrically connected to the meter before the voltage supply contact.
In a sixth principal aspect, the present invention provides a meter for use in combination with a test strip. The test strip includes a working electrode, a counter electrode, a pair of fill-detect electrodes, and an auto-on conductor. The meter comprises a strip connector for receiving the test strip, a processor, a memory, a plurality of machine instructions stored in the memory and executable by the processor for performing a test strip sequence, and a data acquisition system controlled by the processor. When the test strip is inserted in the strip connector, the data acquisition system applies at least a first voltage between the working and counter electrodes and measures any resulting current flowing between the working and counter electrodes, applies at least a second voltage between the fill-detect electrodes and measures any resulting current flowing between the fill-detect electrodes, and measures a voltage drop across the auto-on conductor. The data acquisition system includes at least one digital-to-analog converter and at least one analog-to-digital converter.
REFERENCES:
patent: 4714874 (1987-12-01), Morris et al.
patent: 4894137 (1990-01-01), Takizawa et al.
patent: 4900424 (1990-02-01), Birth et al.
patent: 5120420 (1992-06-01), Nankai et al.
patent: 5128015 (1992-07-01), Szuminsky et al.
patent: 5141868 (1992-08-01), Shanks et al.
patent: 5264103 (1993-11-01), Yoshioka et al.
patent: 5266179 (1993-11-01), Nankai et al.
patent: 5288636 (1994-02-01), Pollmann et al.
patent: 5352351 (1994-10-01), White et al.
patent: 5366609 (1994-11-01), White et al.
patent: 5395504 (1995-03-01), Saurer et al.
patent: 5437999 (1995-08-01), Diebold et al.
patent: 5438271 (1995-08-01), White et al.
patent: 5494562 (1996-02-01), Maley et al.
patent: 5502396 (1996-03-01), Desarzens et al.
patent: 5508171 (1996-04-01), Walling et al.
patent: 5526120 (1996-06-01), Jina et al.
patent: 5575895 (1996-11-01), Ikeda et al.
patent: 5582697 (1996-12-01), Ikeda et al.
patent: 5589045 (1996-12-01), Hyodo
patent: 5628890 (1997-05-01), Carter et al.
patent: 5650062 (1997-07-01), Ikeda et al.
patent: 5682884 (1997-11-01), Hill et al.
patent: 5708247 (1998-01-01), McAleer et al.
patent: 5720862 (1998-02-01), Hamamoto et al.
patent: 5762770 (1998-06-01),
Bell Douglas E.
Neel Gary T.
Voss Houston F.
Wong T. Philip
Home Diagnostics, Inc.
McDonnell & Boehnen Hulbert & Berghoff
Wallenhorst Maureen M.
LandOfFree
System and methods for blood glucose sensing does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with System and methods for blood glucose sensing, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and System and methods for blood glucose sensing will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3311852