JPS61271424A - Blood component quantitative measuring device - Google Patents

Abstract

PURPOSE:To prevent a sensor from being used in the nonlinear operation region thereof and enable the sensor to measure a blood component to the approximate limit of the linear region of the sensor. CONSTITUTION:A sensor 1 detects a predetermined blood component in a reactor. Arithmetic means 2A obtains the value of the predetermined blood component from the difference between the outputs of the sensor 1 before and after a blood sample is injected into the reactor. The result of the calculation by the means 2A is displayed on a display 3. Further, the output of the sensor 1 after the blood sample is injected into the reactor is compared with the threshold of an alarm smaller than the limit of the linear operation of the sensor 1 by a prescribed value. When the output of the sensor 1 exceeds the threshold value smaller than the upper limit output value of the linear operation region of the sensor 1 by the prescribed value, comparator means 2B produces an output and an alarm unit 4 operates in response to the output of the comparator means 2B.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a batch-type blood component quantitative meter that measures, for example, glucose, cholesterol, uric acid, etc. in surface fluid.

[Background technology]

The sensor for measuring blood components, such as glucose, is
It has a glucose value-sensor output current characteristic as shown in the figure, and has a drawback that when the glucose value exceeds the value P, the linearity of input and output of the sensor deteriorates.

To avoid using the sensor in the non-linear characteristic region,
In conventional blood component quantitative meters, the detection range of the sensor is adjusted to be sufficiently small, and it also has a mechanism to replace the buffer solution and blood sample with a pump or the like after each measurement to prevent the sensor output from increasing. ing.

However, with the above configuration, it is difficult to measure many blood samples in a short time, and the tlU
Because it requires a mechanism to replace F fluid and blood samples, it is expensive, and it is extremely difficult for patients with diabetes to purchase it personally and measure blood components such as glucose at home. Ta.

[Purpose of the invention]

The present invention has a simple and inexpensive configuration, can prevent the sensor from being used in a non-linear operating region, and can continuously measure blood components for a large number of blood samples up to almost the limit of the sensor's linear operating region. It is an object of the present invention to provide a blood component quantification needle that can eliminate the need for a liquid exchange mechanism in a reaction tank and shorten the time required to measure a large number of blood samples.

[Disclosure of the invention]

As shown in FIG. 1, the blood component quantitative meter of the present invention includes a sensor 1 that detects a predetermined blood component in a reaction tank, an output of the sensor 1 before injection of a blood sample into the reaction tank, and a sensor 1 that detects a predetermined blood component in a reaction tank. A calculating means 2A for determining a predetermined blood component value of the blood sample from the difference in the output of the sensor 1 after the blood sample is injected into the reaction tank; 2A, and the output of the sensor 1 after the blood sample is injected into the reaction tank is compared with a preset alarm threshold that is smaller than the linear operating limit of the sensor 1 by a predetermined value. Comparing means 2B that generates an output when the output of the sensor 1 exceeds an alarm threshold that is smaller by a predetermined value than the upper limit output value of the linear operating region of the sensor I, and an alarm that responds to the output of the comparing means 2B. 4.

In this way, the blood component value of the blood sample is calculated from the difference in the output of the sensor before and after the blood sample is injected into the reaction tank, and the sensor output after the blood sample is injected into the reaction tank is calculated by calculating the sensor output within the linear operating region of the sensor. Compared to the alarm threshold value that is a predetermined value smaller than the upper limit output value, an alarm is issued when the sensor output exceeds the alarm threshold value, making it easy and inexpensive to use the sensor in non-linear operating ranges. In addition, blood components can be measured continuously on a large number of blood samples up to almost the limit of the sensor's linear operating range, eliminating the need for a liquid exchange mechanism in the reaction tank, and The time required for sample measurement can be reduced.

Embodiment An embodiment of the present invention will be explained based on FIGS. 2, 3, 4, 5A and 5B. For example, a blood component quantitative meter for measuring glucose level is shown in FIG. like,
A sensor 1 that reacts with glucose is installed in a reaction tank (not shown) containing a buffer solution, a calibration solution, and a blood sample, and a constant voltage is applied to one end of the sensor 1 to generate a stabilized voltage of usually about -0.7V. The other end of the sensor 1 is connected to the inverting input end of the operational amplifier OP of the voltage conversion circuit 6.

The sensor 1 generates a current i proportional to the glucose value in response to glucose in the reaction tank, and this current i is generated from an operational amplifier OP and a resistor R connected between its output terminal and inverting input terminal. The voltage conversion circuit 6 converts the voltage V (=iR
) will be converted to

The voltage V output from the voltage conversion circuit 6 is converted into a digital value by the A/D conversion circuit 7 and input to the arithmetic processing circuit 2.

The arithmetic processing circuit 2 has the functions of the arithmetic means 2A and the comparison means 2B in FIG. 1, and stores digital values input from the A/D conversion circuit 7 and the first memory 8. 2nd memory 9
．． The contents of the third memory 10 and the fourth memory 11 are processed to determine the amount of glucose in the blood sample.
In addition to outputting the glucose value per unit, an alarm output is generated when the output of the sensor 1 exceeds an alarm threshold value that is a predetermined value smaller than the upper limit output value of the linear operation region.

Then, the glucose value output from the arithmetic processing circuit 2 is converted into display data by the display circuit 12 and digitally displayed by the digital display 3, and an alarm device 4 such as a buzzer is activated by the alarm output to cause a reaction. The amount of glucose in the tank is close to the upper limit of the linear operating range of the sensor (notifies that the detection accuracy has reached its limit and prompts to replace the liquid in the reaction tank).

Next, the measurement procedure and operation of the arithmetic processing circuit 2 in this blood component quantitative meter will be explained in detail.

First, a predetermined amount of calibration solution is injected into a reaction tank containing a buffer solution. As a result, the sensor 1 reacts to a predetermined amount of glucose in the calibration solution, and the output current i becomes level to as shown in FIG. This output current i is converted into a voltage by a voltage conversion circuit 6, further converted into a digital value by an A/D conversion circuit 7, and input to the arithmetic processing circuit 2.

At this time, the arithmetic processing circuit 2 stores data corresponding to the alarm threshold in the fourth memory 11 as shown in FIG. 5A,
Thereafter, the digital value input from the A/D conversion circuit 7 is stored in the first memory 8 as a reference value for calibration, and this digital value is also stored in the second memory 9 and the third memory IO.

Next, when the first blood sample is additionally injected into the reaction tank, the sensor 1 reacts with the glucose in the first blood sample, and the output current i of the sensor 1 becomes equal to the glucose value in the predetermined amount of the calibration solution. The level i corresponds to the sum of the glucose value of the first blood sample.

The output current i of the sensor 1 is converted into a digital value and input to the arithmetic processing circuit 2 in the same manner as described above.

At this time, the arithmetic processing circuit 2 performs A and A as shown in FIG. 5B.
/ The digital value input from the D conversion circuit 7 is stored in the third memory 10, and the contents of the third memory 10 (digital value at the time of current measurement) and the contents of the second memory 9 (digital value at the time of calibration) are respectively stored. The content of the second memory 9 is read out and the content of the second memory 9 is subtracted from the content of the third memory 10 to obtain a difference digital value corresponding only to the glucose value of the first blood sample, and the content of the first memory 8 is read out and the difference digital value is calculated based on the glucose value of the first blood sample. The ratio between the digital value and the content of the first memory 8 is calculated, and the data of the glucose value per 100 mn of the calibration solution (
) stored in memory in advance), the first
The glucose level of the second blood sample was 100mj! The glucose value of the first blood sample is determined by weight and sent to the display circuit 12, and the display 3 digitally displays the glucose value of the first blood sample. After this, the contents of the third memory 10 are read out and the second
Update and store in Memozo 9. Furthermore, after this, the contents of the third memory 10 are read out, and the contents of the fourth memory 11 (corresponding to a predetermined value, for example, a glucose value of 300 mg/aj (directly The digital value corresponding to the alarm threshold value ix subtracted by
The contents of 0 and the contents of the fourth memory 11 are compared, and when the contents of the third memory 10 are larger than the contents of the fourth memory 1, an alarm is output as the detection accuracy of the sensor 1 has reached its limit. is generated and the alarm 4 is activated. Note that during the first blood sample injection, as is clear from FIG. 4, the output current i of the sensor I is at level 11, which is lower than the alarm threshold value i1, so no alarm output is generated.

After this, when the second blood sample is additionally injected into the reaction tank, the sensor 1 reacts with the glucose in the second blood sample, and the output current i of the sensor 1 becomes equal to the glucose value in the predetermined amount of the calibration solution. The level is 12, which corresponds to the sum of the glucose values of the first and second blood samples.

The output current i of the sensor 1 is converted into a digital value and input to the arithmetic processing circuit 2 in the same manner as described above.

At this time, the arithmetic processing circuit 2 stores the digital value input from the A/D conversion circuit ¥&7 in the third memory 10, and stores the contents of the third memory 10 (digital value at the time of current measurement) and the second memory 9 (digital values from the previous measurement) are read out, and the contents of the second memory 9 are read out from the contents of the third memory 10.
A difference digital value corresponding only to the glucose value of the second blood sample is obtained by subtracting the content of the second blood sample, the content of the first memory 8 is read out, and the ratio of the difference digital value and the content of the first memory 8 is calculated. and then add 10% of the calibration solution to this ratio.
0m7! The glucose value of the first blood sample is determined by the weight per 100 m/t by multiplying the data of the glucose value per 100 m/t (previously stored in the memory), and the result is sent to the display circuit 12. digitally display the glucose value of the blood sample. Thereafter, the contents of the third memory 10 are read out and updated and stored in the second memory 9. Furthermore, after this, the contents of the third memory 10 are read out, and the contents of the fourth memory II (sensor 1
A digital value corresponding to an alarm threshold ix obtained by subtracting a predetermined value, for example, a value corresponding to a glucose value of 300 mg/d1 from the output current value at the upper limit of the linear operation region of The contents of memory 10 and the fourth
The content of the memory 11 is compared with the content of the third memory 0, and when the content of the third memory 0 becomes larger than the content of the fourth memory 11, an alarm output is generated because the detection accuracy of the sensor 1 has reached its limit, and the alarm 4 is activated. make it work. It should be noted that even during the second blood sample injection, as is clear from FIG. 4, the output current i of the sensor is at level 12, which is lower than the alarm threshold mx, so no alarm output is generated.

After this, when a third blood sample is additionally injected into the reaction tank, the glucose value of the second blood sample is displayed in the same manner as in the measurement.

However, the output current l of the sensor l reaches the level i3 and exceeds the alarm threshold value 1x, and an alarm output is generated. In addition, in Fig. 4, an alarm is issued at the time of the third blood sample injection, but this is just an example, and the number of consecutive blood sample injections may vary depending on the characteristics of the sensor 1 or the glucose value of the blood sample. It is clear that this will change.

When the above alarm occurs, the liquid in the reaction tank is discarded, a new buffer is added, and the fourth and subsequent blood samples are sequentially injected, and the glucose value of each blood sample is displayed in the same manner as above. Also, if the glucose value in the reaction tank reaches the detection accuracy limit of sensor 1, an alarm will be issued again.
This will encourage fluid exchange. At this time, it is only necessary to inject the calibration liquid first, and there is no need to inject the calibration liquid after the first liquid exchange.

In this way, in this embodiment, a value smaller than the upper limit output current value at which the sensor 1 operates linearly by a predetermined value is stored in the fourth memory as the alarm threshold, and the output current of the sensor 1 is set to the alarm threshold. By generating an alarm when the value exceeds the value and prompting for liquid replacement in the reaction tank, it is possible to prevent sensor 1 from being used in the non-linear operating range with a simple and inexpensive configuration, and it also prevents sensor 1 from being used in the non-linear operating range. Blood components can be continuously measured on as many blood samples as possible, eliminating the need for a liquid exchange mechanism in the reaction tank and shortening the time required to measure a large number of blood samples.

In the above embodiment, a buzzer or the like is used as the alarm 4, but the WI may be set by blinking the light emitting element, or the IF@ may be set by blinking the display 3 itself. good.

Further, in the above embodiment, the first memory 8. Second memory9.
Third memory 10. Although the fourth memory 11 was separate from the arithmetic processing circuit 2, they can be integrated into one by using a one-chip CPU.

Further, in the above embodiment, a sensor for measuring glucose values has been described, but by changing the sensor 1, other blood components such as cholesterol and uric acid can be similarly detected.

Effects of the Invention The blood component determination needle of the present invention is configured to determine the blood component value of a blood sample from the difference in sensor output before and after the blood sample is injected into the reaction tank, and the blood component value of the sensor after the blood sample is injected into the reaction tank. The output is compared with an alarm threshold that is a predetermined value smaller than the upper limit output value of the sensor's linear operating range, and an alarm is issued when the sensor output exceeds the alarm threshold. It is possible to prevent the sensor from being used in the non-linear operating range, and it is possible to continuously measure blood components on a large number of blood samples up to the limit of the linear operating range of the sensor. This can be made unnecessary and the time required to measure a large number of blood samples can be shortened.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a blood component determination needle of the present invention, FIG. 2 is a block diagram of an embodiment of the present invention, and FIG.
The figure is a sensor input/output characteristic diagram, and Figure 4 is a diagram showing changes in sensor output when a calibration solution and blood sample are injected.
FIGS. 5A and 5B are flowcharts showing the operation of the arithmetic processing circuit. 1...Sensor, 2A...Arithmetic circuit, 2B...Comparison circuit, 3...Display device, 4...Alarm device 2 crushing IiL power raccoon circuit! Figure 1 Figure 5A Figure 5B

Claims (2)

[Claims] (1) A sensor that detects a predetermined blood component in the reaction tank;
calculation means for calculating a predetermined blood component value of the blood sample from the difference between the output of the sensor before the blood sample is injected into the reaction tank and the output of the sensor after the blood sample is injected into the reaction tank; a display for displaying the calculation results of the calculation means; and an alarm threshold value that sets the output of the sensor after the blood sample is injected into the reaction tank to be smaller than the preset upper limit output value of the linear operation region of the sensor by a predetermined value. A blood component quantitative meter comprising a comparison means that generates an output when the output of the sensor exceeds the alarm threshold, and an alarm that responds to the output of the comparison means. (2) The blood component quantitative meter according to claim (1), wherein the predetermined value is set to 300 mg/dl.