ELECTRICAL IMPEDANCE HEMATOCRIT AND HBA1C BIOSENSOR COMPRISING SAMPLE PLATE AND SAMPLE APPARATUS

• US 20150068926A1
• Filed: 04/12/2013
• Published: 03/12/2015
• Est. Priority Date: 04/13/2012
• Status: Active Grant

• Current Assignee: Smartcare Technologies Limited
• Original Assignee: Smartcare Technologies Limited
• Inventors: Ainger, Phillip J., Bryan, Matthew Robert
• Granted Patent: US 10,641,724 B2
• Time in Patent Office: Days
• US Class Current: 205/792
• CPC Class Codes: G01N 27/3271 Amperometric enzyme electrodes for analytes in body fluids, e.g. glucose in blood amperometry per se G01N27/49; aspects concerning the enzyme reagent C12Q1/001
• CPC Class Codes: G01N 27/416 Systems G01N27/27 takes precedence
• CPC Class Codes: G01N 33/48707 by electrical means G01N33/49, G01N33/493 take precedence
• CPC Class Codes: G01N 33/492 Determining multiple analytes

Abstract

A sampling plate (1) is provided comprising a sample zone (2) for receiving a liquid sample, and two drive electrodes (3, 4) with separate respective electrode terminals spaced by a spacing for receiving a the liquid sample within the sample zone for use in driving an electrical signal through the sample. Two sensing electrodes (5, 6) are provided with separate respective electrode terminals spaced between the electrode terminals of the two drive electrodes for use in sensing an electrical signal generated by the drive electrodes within a the sample. A sampling apparatus (15) is provided for use with the plate.

Claims

1. A sampling plate comprising:

a sample zone for receiving a liquid sample;

two drive electrodes with separate respective electrode terminals spaced by a spacing for receiving a said liquid sample within the sample zone for use in driving an electrical signal through the sample;

two sensing electrodes with separate respective electrode terminals spaced between the electrode terminals of the two drive electrodes for use in sensing an electrical signal generated by the drive electrodes within a said sample.

2. A sampling plate according to claim 1 in which the two sensing electrode terminals present to each other opposing sides which define between them an elongate sensing gap extending along the sample zone for receiving said sample therein.

3. A sampling plate according to claim 1 in which the two drive electrode terminals present to each other opposing sides which define between them an elongate drive gap extending along the sample zone for receiving said sample therein whereby the drive electrodes are adapted to drive electrical signal transversely across the drive gap.

4. A sampling plate according to claim 3 in which the two sensing electrode terminals present to each other opposing sides which define between them an elongate sensing gap extending along the sample zone for receiving said sample therein, wherein the sensing gap extends along the drive gap.

6. A sensor according to claim 1 in which a said drive electrode terminal and an adjacent sensing electrode terminal present to each other opposing sides which define between them an elongate partitioning gap extending along the sample zone to define a partition between the adjacent terminals within the sample zone.

8. A sampling plate according to claim 1 in which the sensing electrode terminals are formed on a surface of the sampling plate within the sample zone.

11. A sampling plate according to claim 2 in which the width of the sensing gap is greater than about 90 microns and less than about 160 microns.

12. A sampling plate according to claim 6 in which the two sensing electrode terminals present to each other opposing sides which define between them an elongate sensing gap extending along the sample zone for receiving said sample therein, wherein the width of the partitioning gap is about 1.5 times the width of the sensing gap.

13. A sampling plate according to claim 1 in which the sample zone comprises a reagent to react with free glucose in the liquid sample.

5. (canceled)

7. (canceled)

9. (canceled)

10. (canceled)

14. (canceled)

15. A sampling apparatus for use in performing electrical measurements on a liquid sample containing blood, the apparatus comprising:

two (or more) current output terminals for outputting an alternating current signal applied therebetween;

an alternating electrical current unit in electrical communication with the two (or more) current output terminals for applying thereto an alternating electrical current of a given amplitude and frequency when a said liquid sample is in electrical connection between the two (or more) current output terminals;

a voltage unit in electrical communication with the two (or more) current output terminals for applying therebetween a direct (DC) electrical potential difference of a given magnitude;

a first voltage input terminal for receiving a first electrical signal externally input thereto and a separate second voltage input terminal for receiving a second electrical signal externally input thereto when said liquid sample is in electrical connection between the first and second voltage input terminals;

voltage detector(s) for measuring a first voltage and a second voltage using said first and second electrical signals, respectively;

a control unit arranged to control the electrical current unit to apply a said alternating electrical current of said given frequency and concurrently to control the voltage unit and the voltage detector(s) to measure said first and second voltages both when said direct electrical potential difference is applied and when said direct electrical potential difference is not applied;

a calculating unit arranged to calculate a first electrical reactance value using the first and second voltages measured when said direct electrical potential difference is applied, and to calculate a second electrical reactance value measured when said direct electrical potential difference is not applied;

wherein the calculating unit is arranged to generate a value representing the concentration of glycated haemoglobin (HbA1c) in the liquid sample according to the first electrical reactance value, the second electrical reactance value and a value representing the relative volume of red blood cells in the liquid sample (haematocrit).

16. A sampling apparatus according to claim 15 in which the given frequency has a value in the range 500 KHz to 1.5 MHz.

20. A sampling apparatus according to claim 15 comprising an integrated circuit arranged for measuring said first voltage and said second voltage, and responsive to the control unit to apply said alternating current accordingly.

23. A sampling apparatus according to claim 15 in which said direct (DC) voltage is substantially constant in value.

17. A sampling apparatus for use in performing electrical measurements on a liquid sample containing blood, the apparatus comprising:

two (or more) current output terminals for outputting an alternating current signal applied therebetween;

an alternating electrical current unit in electrical communication with the two (or more) current output terminals for applying therebetween an alternating electrical current of a given amplitude and frequency, when a said liquid sample is in electrical connection between the two (or more) current output terminals;

a first voltage input terminal for receiving a first electrical signal externally input thereto and a separate second voltage input terminal for receiving a second electrical signal externally input thereto, when said liquid sample is in electrical connection between the first and second voltage input terminals;

voltage detector(s) for measuring a first voltage and a second voltage using said first and second electrical signals, respectively;

a control unit arranged to control the electrical current unit to apply a said alternating electrical current at a first frequency and concurrently to control the voltage detector(s) to measure said first and second voltages, and to further control the electrical current unit to apply said alternating electrical current at a second frequency exceeding the first frequency and concurrently to control the voltage detector(s) to measure said first and second voltages;

a calculating unit arranged to calculate a first electrical resistance value using the first and second voltages measured at said first frequency, and a second electrical resistance value and a reactance value using said first and second voltages measured at said second frequency;

wherein the calculating unit is arranged to generate a value representing the relative volume of red blood cells in the liquid sample (haematocrit) according to the first and second electrical resistance values and the electrical reactance value.

21. A sampling apparatus according to claim 17 in which the first frequency has a value in the range 1 KHz to 150 KHz.

22. A sampling apparatus according to claim 17 in which the second frequency has a value in the range 500 KHz to 1.5 MHz.

18. (canceled)

19. (canceled)

24. A sample measurement method for performing electrical measurements on a liquid sample containing blood, the method comprising:

receiving the liquid sample on a sample plate comprising electrode terminals which are separated by a spacing adapted to be bridged by blood from the liquid sample and which comprise a reagent to react with free glucose in the liquid sample; and

applying to the electrodes an alternating electrical current having a given frequency to generate a first alternating potential difference across the spacing between the electrode terminals;

applying between the electrode terminals a substantially direct (DC) electrical potential difference of a given magnitude;

determining a value of a first electrical reactance of the liquid sample bridging said spacing for said given frequency;

removing the substantially direct (DC) electrical potential difference from between the electrode terminals;

applying to the electrodes the alternating electrical current having said given frequency to generate a second alternating potential difference across the spacing between the electrode terminals;

determining a value of a second electrical reactance of the liquid sample bridging said spacing for said given frequency;

generating a value representing the concentration of glycated haemoglobin (HbA1c) in the blood within the sample according to the first electrical reactance value, the second electrical reactance value and a value of the relative volume of red blood cells in the liquid sample (haematocrit).

27. A sample measurement method according to claim 24 in which said direct (DC) voltage is substantially constant in value.

28. A sample measurement method according to claim 27 in which said direct (DC) voltage is substantially constant in value.

25. A sample measurement method for performing electrical measurements on a liquid sample containing blood, the method comprising:

receiving the liquid sample on a sample plate comprising electrode terminals which are separated by a spacing adapted to be bridged by blood from the liquid sample; and

applying to the electrodes an alternating electrical current having a first signal frequency to generate a first alternating potential difference across the spacing between the electrode terminals;

determining a value of a first electrical resistance of the liquid sample bridging said spacing for said first signal frequency;

applying to the electrodes an alternating electrical current having a second signal frequency exceeding said first signal frequency to generate a second alternating potential difference across the spacing between the electrode terminals;

determining a value of a second electrical resistance and a value of a reactance of the liquid sample bridging said spacing for said second signal frequency;

generating a value for the relative volume of red blood cells (haematocrit) in the liquid sample according to the first electrical impedance value and the second electrical impedance value.

26. (canceled)