Concentration measuring method and concentration measuring device

• US 20040232009A1
• Filed: 04/12/2004
• Published: 11/25/2004
• Est. Priority Date: 10/12/2001
• Status: Active Grant

• Current Assignee: ARKRAY, Inc
• Original Assignee: ARKRAY, Inc
• Inventors: Kado, Kotaro, Oura, Yoshimi, Okuda, Hisashi
• Granted Patent: US 7,491,310 B2
• Time in Patent Office: Days
• US Class Current: 205/789
• CPC Class Codes: G01N 27/3274 Corrective measures, e.g. error detection, compensation for temperature or hematocrit, calibration coding of calibration information G01N33/48771

Abstract

The present invention relates to a technique for measuring the concentration of a particular component in a sample liquid using a test tool (2). The test tool (2) includes a first through a third detection elements (31a-33a) arranged in the mentioned order in the moving direction of the sample liquid for measuring an electro-physical quantity. The present invention provides a concentration measuring method which includes a first detection step for detecting whether or not liquid conduction is established between the first and the second detection elements (31a, 32a), a second detection step for detecting whether or not liquid conduction is established between the second and the third detection elements (31a, 33a), a measurement step for measuring an electro-physical quantity by using the first through the third detection elements (31a-33a), and a concentration computation step for computing the concentration of the particular component based on the electro-physical quantity. The present invention also provides a concentration measuring apparatus (1) for realizing the concentration measuring method.

Claims

1. A concentration measuring method for measuring concentration of a particular component in a sample liquid using a test tool;

the test tool comprising;

a capillary for moving the sample liquid, and a first through third detection elements for measuring an electro-physical quantity, the first through the third detection elements being arranged in the mentioned order from an upstream side toward a downstream side in a moving direction of the sample liquid;

wherein the method comprises;

a first detection step for detecting whether or not liquid conduction is established between the first detection element and the second detection element;

a second detection step for detecting whether or not liquid conduction is established between the second detection element and the third detection element;

a measurement step for measuring an electro-physical quantity for computation by using at least two of the first through the third detection elements; and

a concentration computation step for computing the concentration of the particular component based on the electro-physical quantity for computation.

2. The concentration measuring method according to claim 1, further comprising a time computation step for computing time taken from the detection of liquid conduction in the first detection step to the detection of liquid conduction in the second conduction step;

wherein the concentration computation step comprises computing the concentration of the particular component while taking the computed time into consideration.

3. The concentration measuring method according to claim 2, wherein the concentration computation step includes data processing operation for correcting, based on a correction value, an electro-physical quantity for computation or a computed value obtained based on the electro-physical quantity for computation;

and

wherein the correction value is obtained by computation based on data showing a relationship between the time taken and the correction value.

4. The concentration measuring method according to claim 1, wherein the second detection step comprises measuring an electro-physical quantity by using all of the first through the third detection elements and determining whether or not liquid conduction is established between the second detection element and the third detection element based on a time history of the electro-physical quantity.

5. The concentration measuring method according to claim 4, wherein the second detection step comprises measuring an electro-physical quantity at a plurality of predetermined measurement time points, computing a variation in current per unit time at each of the measurement time points, and determining that liquid conduction is established between the second detection element and the third detection element when the variation in current is greater than a predetermined threshold value.

6. The concentration measuring method according to claim 4, wherein the second detection step comprises computing a difference between an electro-physical quantity measured at a certain measurement time point and an electro-physical quantity measured at another measurement time point directly before said certain measurement time point and determining that liquid conduction is established between the second detection element and the third detection element when the difference is greater than a predetermined threshold value.

7. The concentration measuring method according to claim 4, wherein the third detection element is larger in surface area than the first detection element in the test tool.

8. The concentration measuring method according to claim 4, wherein the concentration computation step comprises computing the concentration of the particular component based on a difference between an electro-physical quantity measured after a predetermined time has elapsed since liquid conduction between the second detection element and the third detection element was detected in the second detection step and another electro-physical quantity measured when liquid conduction between the second detection element and the third detection element is detected in the second step.

9. The concentration measuring method according to claim 4, further comprising a time computation step for computing time taken from the detection of liquid conduction in the first detection step to the detection of liquid conduction in the second conduction step;

wherein the concentration computation step comprises computing the concentration of the particular component while taking the computed time into consideration.

10. The concentration measuring method according to claim 2, wherein the sample liquid contains a coexisting component which causes an error in the concentration measurement of the particular component;

and

wherein the time taken is figured out as a reflection of influence of the coexisting component.

11. The concentration measuring method according to claim 10, wherein the sample liquid is blood containing blood cell components as the coexisting component.

12. The concentration measuring method according to claim 11, wherein the particular component is glucose.

13. A concentration measuring apparatus for measuring concentration of a particular component in a sample liquid using a test tool;

the test tool comprising;

a capillary for moving the sample liquid, and a first through a third detection elements for measuring an electro-physical quantity, the first through the third detection elements being arranged in the mentioned order from an upstream side toward a downstream side in a moving direction of the sample liquid;

wherein the apparatus comprises;

a detector for detecting whether or not liquid conduction is established between the first detection element and the second detection element as well as between the second detection element and the third detection element;

an electro-physical quantity measurer for measuring an electro-physical quantity for computation by using at least two of the first through the third detection elements; and

a computation unit for computing the concentration of the particular component based on the electro-physical quantity for computation.

14. The concentration measuring apparatus according to claim 13, further comprising a voltage application unit for applying a voltage across at least two detection elements selected from the first through the third detection elements;

wherein the electro-physical quantity measurer measures a current as the electro-physical quantity when the voltage application means applies the voltage.

15. The concentration measuring apparatus according to claim 13, wherein the computation unit computes time taken from the establishment of liquid conduction between the first detection element and the second detection element to the establishment of liquid conduction between the second detection element and the third detection element and computes the concentration of the particular component while taking the computed time into consideration.

16. The concentration measuring apparatus according to claim 13, wherein the electro-physical quantity measurer measures an electro-physical quantity at a plurality of measurement time points with predetermined intervals, and

wherein the detector determines whether or not liquid conduction is established between the second detection element and the third detection element based on a time-course of the electro-physical quantity.

17. The concentration measuring apparatus according to claim 16, wherein the detector computes a variation in current per unit time at each of the measurement time points and determines that liquid conduction is established between the second detection element and the third detection element when the variation in current is greater than a predetermined threshold value.

18. The concentration measuring apparatus according to claim 16, wherein the detector computes a difference between an electro-physical quantity measured at a certain measurement time point and an electro-physical quantity measured at another measurement time point directly before said certain measurement time point and determines that liquid conduction is established between the second detection element and the third detection element when the difference is greater than a predetermined threshold value.

19. The concentration measuring apparatus according to claim 16, wherein the computation unit computes the concentration of the particular component based on a difference between an electro-physical quantity measured after a predetermined time has elapsed since liquid conduction between the second detection element and the third detection element was detected by the detector and another electro-physical quantity measured when liquid conduction between the second detection element and the third detection element is detected by the detector.