Determining analyte concentrations in biological fluids with abnormal output detection

Patent metadata

Field	Value
Publication number	US-9301717-B2
Application number	US-201213536310-A
Country	US
Kind code	B2
Filing date	Jun 28, 2012
Priority date	May 8, 2006
Publication date	Apr 5, 2016
Grant date	Apr 5, 2016

Abstract

A biosensor has an abnormal output detection system that determines whether an output signal from the redox reaction of an analyte has a normal or abnormal shape or configuration. The abnormal output detection system improves the accuracy and precision of the biosensor in determining whether an output signal has a shape or configuration that may not provide an accurate and/or precise analysis of a biological fluid. The biosensor generates an output signal in response to the redox reaction of the analyte. The biosensor normalizes the output signal and compares the normalized output signal with one or more control limits. The biosensor may generate an error signal when the normalized output signal is not within the control limits.

First claim

The invention claimed is:

1. A biosensor for determining an analyte concentration in a biological fluid, comprising:
a sensor strip having a sample interface on a base, where the sample interface is adjacent to a reservoir formed by the base; and
a measuring device having a processor connected to a sensor interface, where the sensor interface has electrical communication with the sample interface;
where the processor directs a signal generator to provide a pulsed input signal to a sample of a biological fluid, the pulses of the input signal separated by relaxations where the electrical signal is off;
where the processor receives an output signal from a redox reaction of an analyte in the sample, where the output signal is responsive to the pulses of the input signal;
where the processor measures the output signal from the redox reaction of the analyte in the sample;
where the processor normalizes the output signal from the redox reaction of the analyte in the sample, where the output signal is responsive to an analyte concentration in the sample, the normalized output signal being indicative of the analyte concentration in the sample;
where the processor compares the normalized output signal from at least two of the pulses separated by relaxations to at least one control limit, where the at least one control limit represents at least one transition of the output signal from normal to abnormal;
where the processor generates an error signal when the normalized output signal is not within the at least one control limit, the error signal being indicative of an error in analysis of the analyte concentration in the sample; and
where the processor calculates a ratio of a first normalized current value from one of the pulses to a second normalized current value from another pulse.

2. The biosensor of claim 1 , where the processor determines a difference between at least one base output value and at least two measured output values of the output signal, where the processor uses at least one base output value in the normalizing of the at least two measured output values.

3. The biosensor of claim 2 , where the input signal includes a gated amperometric input signal including pulses and the output signal is responsive to the pulses of the gated amperometric input signal.

4. The biosensor of claim 3 , where the output signal comprises at least five pulses.

5. The biosensor of claim 2 , where the at least one base output value is a different measured output value of the output signal than at least one of the at least two measured output values.

6. The biosensor of claim 5 , where the normalized current value of the fourth pulse, R 4 , is represented by the following equation:

R
4

=

i

4
,
8

i

4
,
1

,

where i 4,1 is the first current value in the fourth pulse and i 4,8 is the last current value in the fourth pulse.

7. The biosensor of claim 5 , where the normalized current value of the fifth pulse, R 5 , is represented by the following equation:

R
5

=

i

5
,
8

i

5
,
1

,

where i 5,1 is the first current value in the fifth pulse and i 5,8 is the last current value in the fifth pulse.

8. The biosensor of claim 5 , where the ratio of the normalized current value of the fourth pulse to the normalized current value of the fifth pulse is represented by the following equation:

Ratio
=

i

4
,
8

*

i

5
,
1

i

4
,
1

*

i

5
,
8

,

where i 4,1 is the first current value in the fourth pulse, i 4,8 is the last current value in the fourth pulse, i 5,1 is the first current value in the fifth pulse, and i 5,8 is the last current value in the fifth pulse.

9. The biosensor of claim 1 , where the processor divides at least one output value of the output signal by a first output value from a pulse of the output signal.

10. The biosensor of claim 1 , where the at least one control limit is predetermined from a statistical analysis of laboratory results.

11. The biosensor of claim 1 , where the input signal comprises a polling input signal and an assay input signal.

12. The biosensor of claim 11 , where the polling input signal has a polling pulse width of less than about 300 ms and a polling pulse interval of less than about 1 sec.

13. The biosensor of claim 11 , where the assay input signal has an assay pulse width of less than about 5 sec, and where the assay input signal has an assay pulse interval of less than about 15 sec.

14. The biosensor of claim 11 , where the processor applies the polling input signal during a polling period of less than about 180 sec, and where the processor applies the assay input signal during an assay period of less than about 180 sec.

15. The biosensor of claim 11 , where the processor applies the polling input signal during a polling period in the range of about 0.1 sec through about 10 sec, and where the processor applies the assay input signal during an assay period in the range of about 1 sec through about 100 sec.

16. The biosensor of claim 11 ,
where the processor applies a polling input signal to the sample for about 1.25 sec, where the polling input signal has a polling pulse width of about 5-10 ms, a polling pulse interval of about 125 ms, and a potential of about 400 mV; and
where the processor applies an assay input signal to the sample for about 7 sec, where th

Assignees

• Carpenter Scott
• Nelson Christine D
• Wu Huan-Ping
• Ascensia Diabetes Care Holdings Ag

Inventors

• Carpenter Scott
• Nelson Christine D
• Wu Huan-Ping

Classifications

• G06F19/18

  Physics · mapped topic

• A61B5/1486

  using enzyme electrodes, e.g. with immobilised oxidase · CPC title

• A61B5/14532

  for measuring glucose, e.g. by tissue impedance measurement · CPC title

• C12Q1/001

  Enzyme electrodes · CPC title

• A61B5/14546 Primary

  for measuring analytes not otherwise provided for, e.g. ions, cytochromes · CPC title