Hand-held test meter with phase-shift-based hematocrit measurement circuit

• US 8,623,660 B2
• Filed: 09/30/2011
• Issued: 01/07/2014
• Est. Priority Date: 09/30/2011
• Status: Active Grant

• Current Assignee: Cilag Gmbh International (Johnson & Johnson), LifeScan IP Holdings, LLC
• Original Assignee: LifeScan Scotland Limited (Johnson & Johnson)
• Inventors: Kraft, Ulrich, Elder, David, Kermani, Mahyar
• Primary Examiner(s): Wallenhorst, Maureen
• Application Number:
  US13/250,525
• Publication Number:
  US 20130084589A1
• Time in Patent Office: 830 Days
• Field of Search: 436/14, 436/63, 436/70, 436/95, 436/149, 436/150, 422/68.1, 422/73, 422/82.01, 422/82.02, 435/14, 435/29, 204/400, 600/365
• US Class Current: 436/70
• CPC Class Codes: G01N 27/3273 Devices therefor, e.g. test element readers, circuitry details not specific to biochemical electrodes G01N33/4875
• CPC Class Codes: G01N 27/3274 Corrective measures, e.g. error detection, compensation for temperature or hematocrit, calibration coding of calibration information G01N33/48771
• CPC Class Codes: Y10T 436/144444 Glucose

Abstract

A hand-held test meter for use with an analytical test strip in the determination of an analyte in a bodily fluid sample includes a housing; a microcontroller block disposed in the housing; and a phase-shift-based hematocrit measurement block. The phase-shift-based hematocrit measurement block includes a signal generation sub-block, a low pass filter sub-block, an analytical test strip sample cell interface sub-block, a transimpedance amplifier sub-block, and a phase detector sub-block. In addition, the phase-shift-based hematocrit measurement block and microcontroller block are configured to measure the phase shift of a bodily fluid sample in a sample cell of an analytical test strip inserted in the hand-held test meter and the microcontroller block is configured to compute the hematocrit of the bodily fluid sample based on the measured phase shift.

Claims

1. A hand-held test meter for use with an analytical test strip in the determination of an analyte in a bodily fluid sample, the hand-held test meter comprising:

a housing;

a microcontroller block disposed in the housing; and

a phase-shift-based hematocrit measurement block disposed in the housing, the phase-shift-based hematocrit measurement block including, in series order;

a signal generation sub-block configured to generate at least a first electrical signal of a first frequency is in the range of 10 kHz to 25 kHz and a second electrical signal of a second frequency in the range of 250 kHz to 500 kHz;

a low pass filter sub-block;

an analytical test strip sample cell interface sub-block;

a transimpedance amplifier sub-block; and

a phase detector sub-block,

wherein the phase-shift-based hematocrit measurement block and microcontroller block are configured to measure the phase shift of a bodily fluid sample in a sample cell of an analytical test strip inserted in the hand-held test meter using both the first signal of the first frequency and the second signal of the second frequency,

wherein the phase-shift-based hematocrit measurement block and microcontroller block are configured such that the signal of the first frequency is employed as a reference signal during the measurement of the phase shift of a bodily fluid sample; and

wherein the microcontroller block is configured to compute the hematocrit of the bodily fluid based on the measured phase shift.

2. The hand-held test meter of claim 1 wherein the bodily fluid sample is a whole blood sample.

3. The hand-held test meter of claim 1 wherein the phase detector sub-block is configured as a rising edge capture phase detector.

4. The hand-held test meter of claim 1 wherein the phase detector sub-block is configured as a dual edge capture phase detector.

5. The hand-held test meter of claim 1 wherein the phase detector sub-block is configured as an XOR phase detector.

6. The hand-held test meter of claim 1 wherein the phase detector sub-block is configured as a synchronous modulation phase detector.

7. The hand-held test meter of claim 1 further including a calibration load sub-block configured in parallel with the analytical test strip sample cell interface sub-block and to provide a phase offset for use in calibration.

8. The hand-held test meter of claim 1 wherein the phase-shift-based hematocrit measurement block and microcontroller block are configured to measure the phase shift of a bodily fluid sample in a sample cell of an analytical test strip inserted in the hand-held test meter by forcing a signal of known frequency through the bodily fluid sample and measuring the phase-shift of the signal.

9. The hand-held test meter of claim 1 wherein the signal generation sub-block is integrated with the microcontroller block.

10. The hand-held test meter of claim 1 wherein the analytical test strip sample cell interface sub-block is configured to operatively interface with the sample cell of the analytical test strip via a first electrode and a second electrode of the analytical test strip disposed in the sample cell.

11. The hand-held test meter of claim 1 wherein the analytical test strip is an electrochemical-based analytical test strip configured for the determination of glucose in a whole blood sample.

12. The hand-held test meter of claim 1 wherein the phase detector sub-block is configured as a Quadratur DEMUX phase detector.

13. A method for employing a hand-held test meter and analytical test strip, the method comprising:

inserting an analytical test strip into a hand-held test meter;

introducing a whole blood sample into a sample cell of the analytical test strip;

measuring a phase shift of the whole blood sample in the sample cell using a phase-shift-based hematocrit measurement block and a microcontroller block of the hand-held test meter;

computing the hematocrit of whole blood sample based on the measured phase shift using the microcontroller block, and

wherein the phase-shift-based hematocrit measurement block and microcontroller block are configured to measure the phase shift of the whole blood sample using a signal of a first frequency in the range of 10 kHz to 25 kHz as a reference signal and a second signal of a second frequency in the range of 250 kHz to 500 kHz.

14. The method of claim 13 further including:

determining an analyte in the introduced whole blood sample using the analytical test strip, hand-held test meter and computed hematocrit.

15. The method of claim 14 wherein the analytical test strip is an electrochemical-based analytical test strip and the analyte is glucose.

16. The method of claim 13 wherein the measuring step includes measuring the phase shift with a phase-shift based measurement circuit block disposed within the hand-held test meter that includes, in series order:

a signal generation sub-block;

a low pass filter sub-block;

an analytical test strip sample cell interface sub-block;

a transimpedance amplifier sub-block; and

a phase detector sub-block.

17. The method of claim 16 wherein the phase detector sub-block is configured as a rising edge capture phase detector.

18. The method of claim 16 wherein the phase detector sub-block is configured as a dual edge capture phase detector.

19. The method of claim 16 wherein the phase detector sub-block is configured as an XOR phase detector.

20. The method of claim 16 wherein the phase detector sub-block is configured as a synchronous modulation phase detector.

21. The method of claim 16 wherein the phase detector sub-block is configured as a Quadratur DEMUX phase detector.